Pursuant to 37 C.F.R. xc2xa71.71(e), Applicants note that a portion of this disclosure contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
The present invention relates to new polypeptides exhibiting granulocyte colony-stimulating factor (G-CSF) activity, to conjugates between a polypeptide exhibiting G-CSF activity and a non-polypeptide moiety, to methods for preparing such polypeptides or conjugates and the use of such polypeptides or conjugates in therapy, in particular for the treatment of neutropenia or leukopenia.
The process by which white blood cells grow, divide and differentiate in the bone marrow is called hematopoiesis (Dexter and Spooncer, Ann. Rev. Cell. Biol., 3:423, 1987). Each of the blood cell types arises from pluripotent stem cells. There are generally three classes of blood cells produced in vivo: red blood cells (erythrocytes), platelets and white blood cells (leukocytes), the majority of the latter being involved in host immune defense. Proliferation and differentiation of hematopoietic precursor cells are regulated by a family of cytokines, including colony-stimulating factors (CSF""s) such as G-CSF and interleukins (Arai et al., Ann. Rev. Biochem., 59:783-836, 1990). The principal biological effect of G-CSF in vivo is to stimulate the growth and development of certain white blood cells known as neutrophilic granulocytes or neutrophils (Welte et al., PNAS-USA 82:1526-1530, 1985, Souza et al., Science, 232:61-65, 1986). When released into the blood stream, neutrophilic granulocytes function to fight bacterial and other infection.
The amino acid sequence of human G-CSF (hG-CSF) was reported by Nagata et al. Nature 319:415-418, 1986. hG-CSF is a monomeric protein that dimerizes the G-CSF receptor by formation of a 2:2 complex of 2 G-CSF molecules and 2 receptors (Horan et al. (1996), Biochemistry 35(15): 4886-96). Aritomi et al. Nature 401:713-717, 1999 have described the X-ray structure of a complex between hG-CSF and the BN-BC domains of the G-CSF receptor. They identify the following hG-CSF residues as being part of the receptor binding interfaces: G4, P5, A6, S7, S8, L9, P10, Q11, S12, L15, K16, E19, Q20, L108, D109, D112, T115, T116, Q119, E122, E123, and L124. Expression of rhG-CSF in Escherichia coli, Saccharomyces cerevisiae and mammalian cells has been reported (Souza et al., Science 232:61-65, 1986, Nagata et al., Nature 319: 415-418, 1986, Robinson and Wittrup, Biotechnol. Prog. 11:171-177, 1985).
Leukopenia (a reduced level of white blood cells) and neutropenia (a reduced level of neutrophils) are disorders that result in an increased susceptibility to various types of infections. Neutropenia can be chronic, e.g. in patients infected with HIV, or acute, e.g. in cancer patients undergoing chemotherapy or radiation therapy. For patients with severe neutropenia, e.g. as a result of chemotherapy, even relatively minor infections can be serious and even life-threatening. Recombinant human G-CSF (rhG-CSF) is generally used for treating various forms of leukopenia/neutropenia. Thus, commercial preparations of rhG-CSF are available under the names filgrastim (Gran(copyright) and Neupogen(copyright)), lenograstim (Neutrogin(copyright) and Granocyte(copyright)) and nartograstim (Neu-up(copyright)). Gran(copyright) and Neupogen(copyright) are non-glycosylated and produced in recombinant E. coli cells. Neutrogin(copyright) and Granocyte(copyright) are glycosylated and produced in recombinant CHO cells and Neu-up(copyright) is non-glycosylated with five amino acids substituted at the N-terminal region of intact rhG-CSF produced in recombinant E. coli cells.
Various protein-engineered variants of hG-CSF have been reported (e.g. U.S. Pat. Nos. 5,581,476, 5,214,132, 5,362,853, 4,904,584 and Riedhaar-Olson et al. Biochemistry 35: 9034-9041, 1996). Modification of hG-CSF and other polypeptides so as to introduce at least one additional carbohydrate chain as compared to the native polypeptide has been suggested (U.S. Pat. No. 5,218,092). It is stated that the amino acid sequence of the polypeptide may be modified by amino acid substitution, amino acid deletion or amino acid insertion so as to effect addition of an additional carbohydrate chain. In addition, polymer modifications of native hG-CSF, including attachment of PEG groups, have been reported (Satake-Ishikawa et al., Cell Structure and Function 17:157-160, 1992, U.S. Pat. No. 5,824,778, U.S. Pat. No. 5,824,784, WO 96/11953, WO 95/21629, WO 94/20069).
Bowen et al., Experimental Hematology 27 (1999), 425-432 disclose a study of the relationship between molecule mass and duration of activity of PEG-conjugated G-CSF mutein. An apparent inverse correlation was suggested between molecular weight of the PEG moieties conjugated to the protein and in vitro activity, whereas in vivo activities increased with increasing molecular weight. It is speculated that a lower affinity of the conjugates act to increase the half-life, because receptor-mediated endocytosis is an important mechanism regulating levels of hematopoietic growth factors.
The commercially available rhG-CSF has a short-term pharmacological effect and must therefore be administered once a day for the duration of the leukopenic state. A molecule with a longer circulation half-life would decrease the number of administrations necessary to alleviate the leukopenia and prevent consequent infections. Another, more significant problem with currently available rG-CSF products is that patients become neutropenic after chemotherapy even after administration of G-CSF. For these patients, it is important to be able to reduce the duration and degree of the neutropenic state as much as possible in order to minimize the risk of serious infections. A further problem is the occurrence of dose-dependent bone pain. Since bone pain is experienced by patients as a significant side effect of treatment with rG-CSF, it would be desirable to provide a rG-CSF product that does not cause bone pain, either by means of a product that inherently does not have this effect or that is effective in a sufficiently small dose that no bone pain is caused. Thus, there is clearly a need for improved recombinant G-CSF-like molecules.
With respect to the half-life, one way to increase the circulation half-life of a protein is to ensure that clearance of the protein, in particular via renal clearance and receptor-mediated clearance, is reduced. This may be achieved by conjugating the protein to a chemical moiety which is capable of increasing the apparent size, thereby reducing renal clearance and increasing the in vivo half-life. Furthermore, attachment of a chemical moiety to the protein may effectively block proteolytic enzymes from physical contact with the protein, thus preventing degradation by non-specific proteolysis. Polyethylene glycol (PEG) is one such chemical moiety that has been used in the preparation of therapeutic protein products. Recently, G-CSF molecule modified with a single, N-terminally linked 20 kDa PEG group (Neulastam) was approved for sale in the United States. This PEGylated G-CSF molecule has been shown to have an increased half-life compared to non-PEGylated G-CSF and thus may be administered less frequently than current G-CSF products, but it does not reduce the duration of neutropenia significantly compared to non-PEGylated G-CSF. Thus, there is still substantial room for improvement of the known G-CSF molecules.
A need therefore still exists for providing novel molecules exhibiting G-CSF activity that are useful in the treatment of leukopenia/neutropenia, and which have are improved in terms of e.g. an increased half-life and in particular a reduction in the duration of neutropenia. The present invention relates to such molecules.
The present invention relates to specific conjugates comprising a polypeptide exhibiting G-CSF activity and a non-polypeptide moiety, methods for their preparation and their use in medical treatment and in the preparation of pharmaceuticals. Accordingly, in a first aspect the invention relates to various specific conjugates comprising a polypeptide exhibiting G-CSF activity and having an amino acid sequence that differs from the known amino acid sequence of human G-CSF as shown in SEQ ID NO:1 in at least one specified altered amino acid residue comprising an attachment group for a non-polypeptide moiety, and having at least one non-polypeptide moiety attached to an attachment group of the polypeptide. These conjugates have a substantially reduced in vitro bioactivity compared to that of non-conjugated hG-CSF, which surprisingly has been shown to result in a more rapid neutrophil recovery. The conjugate of the present invention thus has one or more improved properties as compared to commercially available rhG-CSF, including increased stimulation of neutrophils, increased functional in vivo half-life, increased serum half-life, reduced side effects, reduced immunogenicity and/or increased bioavailability. Consequently, medical treatment with a conjugate of the invention offers a number of advantages over the currently available G-CSF compounds.
In a further aspect the invention relates to polypeptides exhibiting G-CSF activity and which form part of a conjugate of the invention. The polypeptides of the invention are contemplated to be useful as such for therapeutic, diagnostic or other purposes, but find particular interest as intermediate products for the preparation of a conjugate of the invention.
In a further aspect the invention relates to a polypeptide conjugate comprising a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence of hG-CSF (with the amino acid sequence shown in SEQ ID NO:1) in at least one amino acid residue selected from an introduced or removed amino acid residue comprising an attachment group for a non-polypeptide moiety, and a sufficient number or type of non-polypeptide moieties to provide the conjugate with an increased half-life and/or a more rapid neutrophil recovery compared to known recombinant G-CSF products.
In a particular aspect the invention relates to a polypeptide conjugate exhibiting G-CSF activity, comprising a polypeptide having the substitutions K16R, K34R, K40R, T105K, and S159K, and optionally a substitution in position H170, e.g. to R, K or Q, relative to the amino acid sequence of hG-CSF shown in SEQ ID NO:1, or in a corresponding position relative to an amino acid sequence having at least 80% sequence identity with SEQ ID NO:1, and having 2-6, typically 3-6 polyethylene glycol moieties with a molecular weight of about 1000-10,000 Da attached to one or more attachment groups of the polypeptide. Where these substitutions are relative to a sequence with at least about 80% sequence identity with SEQ ID NO:1, the degree of sequence identity is typically at least about 90% or 95%, such as at least about 96%, 97% 98% or 99%.
In still further aspects the invention relates to methods for preparing a conjugate of the invention, including nucleotide sequences encoding a polypeptide of the invention, expression vectors comprising such a nucleotide sequence, and host cells comprising such a nucleotide sequence or expression vector.
In final aspects the invention relates to a composition comprising a conjugate or polypeptide of the invention, a method for preparing a pharmaceutical composition, use of a conjugate or composition of the invention as a pharmaceutical, and a method of treating a mammal with such composition. In particular, the polypeptide, conjugate or composition of the invention may be used to prevent infection in cancer patients undergoing certain types of radiation therapy, chemotherapy, and bone marrow transplantations, to mobilize progenitor cells for collection in peripheral blood progenitor cell transplantations, for treatment of severe chronic or relative leukopenia, irrespective of cause, and to support treatment of patients with acute myeloid leukemia. Additionally, the polypeptide, conjugate or composition of the invention may be used for treatment of AIDS or other immunodeficiency diseases as well as bacterial infections.
Definitions
In the context of the present application and invention the following definitions apply:
The term xe2x80x9cconjugatexe2x80x9d is intended to indicate a heterogeneous molecule formed by the covalent attachment of one or more polypeptides, typically a single polypeptide, to one or more non-polypeptide moieties such as polymer molecules, lipophilic compounds, carbohydrate moieties or organic derivatizing agents. The term covalent attachment means that the polypeptide and the non-polypeptide moiety are either directly covalently joined to one another, or else are indirectly covalently joined to one another through an intervening moiety or moieties, such as a bridge, spacer, or linkage moiety or moieties. Preferably, the conjugate is soluble at relevant concentrations and conditions, i.e. soluble in physiological fluids such as blood. The term xe2x80x9cnon-conjugated polypeptidexe2x80x9d may be used about the polypeptide part of the conjugate.
The term xe2x80x9cpolypeptidexe2x80x9d may be used interchangeably herein with the term xe2x80x9cproteinxe2x80x9d.
The xe2x80x9cpolymer moleculexe2x80x9d is a molecule formed by covalent linkage of two or more monomers, wherein none of the monomers is an amino acid residue, except where the polymer is human albumin or another abundant plasma protein. The term xe2x80x9cpolymerxe2x80x9d may be used interchangeably with the term xe2x80x9cpolymer moleculexe2x80x9d. The term is intended to cover carbohydrate molecules, although, normally, the term is not intended to cover the type of carbohydrate molecule which is attached to the polypeptide by in vivo Nxe2x80x94 or O-glycosylation (as further described below), since such molecule is referred to herein as xe2x80x9can oligosaccharide moietyxe2x80x9d. Except where the number of polymer molecule(s) is expressly indicated every reference to xe2x80x9ca polymerxe2x80x9d, xe2x80x9ca polymer moleculexe2x80x9d, xe2x80x9cthe polymerxe2x80x9d or xe2x80x9cthe polymer moleculexe2x80x9d contained in a polypeptide of the invention or otherwise used in the present invention shall be a reference to one or more polymer molecule(s).
The term xe2x80x9cattachment groupxe2x80x9d is intended to indicate an amino acid residue group of the polypeptide capable of coupling to the relevant non-polypeptide moiety. For instance, for polymer conjugation, in particular to PEG, a frequently used attachment group is the xcex5-amino group of lysine or the N-terminal amino group. Other polymer attachment groups include a free carboxylic acid group (e.g. that of the C-terminal amino acid residue or of an aspartic acid or glutamic acid residue), suitably activated carbonyl groups, oxidized carbohydrate moieties and mercapto groups. Useful attachment groups and their matching non-peptide moieties are apparent from the table below.
For in vivo N-glycosylation, the term xe2x80x9cattachment groupxe2x80x9d is used in an unconventional way to indicate the amino acid residues constituting an N-glycosylation site (with the sequence N-Xxe2x80x2-S/T/C-Xxe2x80x3, wherein Xxe2x80x2 is any amino acid residue except proline, Xxe2x80x3 any amino acid residue which may or may not be identical to Xxe2x80x2 and which preferably is different from proline, N is asparagine, and S/T/C is either serine, threonine or cysteine, preferably serine or threonine, and most preferably threonine). Although the asparagine residue of the N-glycosylation site is where the oligosaccharide moiety is attached during glycosylation, such attachment cannot be achieved unless the other amino acid residues of the N-glycosylation site are present. Accordingly, when the non-peptide moiety is an oligosaccharide moiety and the conjugation is to be achieved by N-glycosylation, the term xe2x80x9camino acid residue comprising an attachment group for the non-peptide moietyxe2x80x9d as used in connection with alterations of the amino acid sequence of the polypeptide of interest is to be understood as meaning that one or more amino acid residues constituting an N-glycosylation site are to be altered in such a manner that either a functional N-glycosylation site is introduced into the amino acid sequence or removed from said sequence.
In the present application, amino acid names and atom names (e.g. CA, CB, NZ, N, O, C, etc.) are used as defined by the Protein DataBank (PDB) (www.pdb.org), which is based on the IUPAC nomenclature (IUPAC Nomenclature and Symbolism for Amino Acids and Peptides (residue names, atom names etc.), Eur. J. Biochem., 138, 9-37 (1984) together with their corrections in Eur. J. Biochem., 152, 1 (1985). The term xe2x80x9camino acid residuexe2x80x9d is intended to indicate any naturally or non-naturally occurring amino acid residue, in particular an amino acid residue contained in the group consisting of the 20 naturally occurring amino acids, i.e. alanine (Ala or A), cysteine (Cys or C), aspartic acid (Asp or D), glutamic acid (Glu or E), phenylalanine (Phe or F), glycine (Gly or G), histidine (His or H), isoleucine (Ile or I), lysine (Lys or K), leucine (Leu or L), methionine (Met or M), asparagine (Asn or N), proline (Pro or P), glutamine (Gln or Q), arginine (Arg or R), serine (Ser or S), threonine (Thr or T), valine (Val or V), tryptophan (Trp or W), and tyrosine (Tyr or Y) residues.
The terminology used for identifying amino acid positions/substitutions is illustrated as follows: F13 indicates position number 13 occupied by a phenylalanine residue in the reference amino acid sequence. F13K indicates that the phenylalanine residue of position 13 has been substituted with a lysine residue. Unless otherwise indicated, the numbering of amino acid residues made herein is made relative to the amino acid sequence of hG-CSF shown in SEQ ID NO:1. Alternative substitutions are indicated with a xe2x80x9c/xe2x80x9d, e.g. Q67D/E means an amino acid sequence in which glutamine in position 67 is substituted with either aspartic acid or glutamic acid. Multiple substitutions are indicated with a xe2x80x9c+xe2x80x9d, e.g. S53N+G55S/T means an amino acid sequence which comprises a substitution of the serine residue in position 53 with an asparagine residue and a substitution of the glycine residue in position 55 with a serine or a threonine residue.
The term xe2x80x9cnucleotide sequencexe2x80x9d is intended to indicate a consecutive stretch of two or more nucleotide molecules. The nucleotide sequence may be of genomic, cDNA, RNA, semisynthetic or synthetic origin, or any combination thereof.
The term xe2x80x9cpolymerase chain reactionxe2x80x9d or xe2x80x9cPCRxe2x80x9d refers to the well-known method for amplification of a desired nucleotide sequence in vitro using a thermostable DNA polymerase.
xe2x80x9cCellxe2x80x9d, xe2x80x9chost cellxe2x80x9d, xe2x80x9ccell linexe2x80x9d and xe2x80x9ccell culturexe2x80x9d are used interchangeably herein and all such terms should be understood to include progeny resulting from growth or culturing of a cell. xe2x80x9cTransformationxe2x80x9d and xe2x80x9ctransfectionxe2x80x9d are used interchangeably to refer to the process of introducing DNA into a cell.
xe2x80x9cOperably linkedxe2x80x9d refers to the covalent joining of two or more nucleotide sequences, by means of enzymatic ligation or otherwise, in a configuration relative to one another such that the normal function of the sequences can be performed. For example, the nucleotide sequence encoding a presequence or secretory leader is operably linked to a nucleotide sequence for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide: a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; a ribosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation. Generally, xe2x80x9coperably linkedxe2x80x9d means that the nucleotide sequences being linked are contiguous and, in the case of a secretory leader, contiguous and in reading phase. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, then synthetic oligonucleotide adaptors or linkers are used, in conjunction with standard recombinant DNA methods.
The term xe2x80x9cintroducexe2x80x9d refers to introduction of an amino acid residue comprising an attachment group for a non-polypeptide moiety, in particular by substitution of an existing amino acid residue, or alternatively by insertion of an additional amino acid residue. The term xe2x80x9cremovexe2x80x9d refers to removal of an amino acid residue comprising an attachment group for a non-polypeptide moiety, in particular by substitution of the amino acid residue to be removed by another amino acid residue, or alternatively by deletion (without substitution) of the amino acid residue to be removed.
When substitutions are performed in relation to a parent polypeptide, they are preferably xe2x80x9cconservative substitutionsxe2x80x9d, in other words substitutions performed within groups of amino acids with similar characteristics, e.g. small amino acids, acidic amino acids, polar amino acids, basic amino acids, hydrophobic amino acids and aromatic amino acids.
Preferred substitutions in the present invention may in particular be chosen from among the conservative substitution groups listed in the table below.
Conservative substitution groups:
The term xe2x80x9cimmunogenicityxe2x80x9d as used in connection with a given substance is intended to indicate the ability of the substance to induce a response from the immune system. The immune response may be a cell or antibody mediated response (see, e.g., Roitt: Essential Immunology (8th Edition, Blackwell) for further definition of immunogenicity). Normally, reduced antibody reactivity will be an indication of reduced immunogenicity. The reduced immunogenicity may be determined by use of any suitable method known in the art, e.g. in vivo in vitro.
The term xe2x80x9cfunctional in vivo half-lifexe2x80x9d is used in its normal meaning, i.e. the time at which 50% of the biological activity of the polypeptide or conjugate is still present in the body/target organ, or the time at which the activity of the polypeptide or conjugate is 50% of the initial value. As an alternative to determining functional in vivo half-life, xe2x80x9cserum half-lifexe2x80x9d may be determined, i.e. the time in which 50% of the polypeptide or conjugate molecules circulate in the plasma or bloodstream prior to being cleared. Alternative terms to serum half-life include xe2x80x9cplasma half-lifexe2x80x9d, xe2x80x9ccirculating half-lifexe2x80x9d, xe2x80x9cserum clearancexe2x80x9d, xe2x80x9cplasma clearancexe2x80x9d and xe2x80x9cclearance half-lifexe2x80x9d. The polypeptide or conjugate is cleared by the action of one or more of the reticuloendothelial systems (RES), kidney, spleen or liver, by receptor-mediated degradation, or by specific or non-specific proteolysis, in particular by the action of receptor-mediated clearance and renal clearance. Normally, clearance depends on size (relative to the cutoff for glomerular filtration), charge, attached carbohydrate chains, and the presence of cellular receptors for the protein. The functionality to be retained is normally selected from proliferative or receptor-binding activity. The functional in vivo half-life and the serum half-life may be determined by any suitable method known in the art as further discussed in the Materials and Methods section below.
The term xe2x80x9cincreasedxe2x80x9d as used about the functional in vivo half-life or serum half-life is used to indicate that the relevant half-life of the conjugate or polypeptide is statistically significantly increased relative to that of a reference molecule, such as a non-conjugated hG-CSF (e.g. Neupogen(copyright)) as determined under comparable conditions. For instance, the relevant half-life may increased by at least about 25%, such as by at least about 50%, e.g. by at least about 100%, 200%, 500% or 1000%.
The term xe2x80x9crenal clearancexe2x80x9d is used in its normal meaning to indicate any clearance taking place by the kidneys, e.g. by glomerular filtration, tubular excretion or tubular elimination. Renal clearance depends on physical characteristics of the conjugate, including size (diameter), symmetry, shape/rigidity and charge. Reduced renal clearance may be established by any suitable assay, e.g. an established in vivo assay. Typically, renal clearance is determined by administering a labeled (e.g. radioactive or fluorescent labeled) polypeptide conjugate to a patient and measuring the label activity in urine collected from the patient. Reduced renal clearance is determined relative to a corresponding reference polypeptide, e.g. the corresponding non-conjugated polypeptide, a non-conjugated corresponding wild-type polypeptide or another conjugated polypeptide (such as a conjugated polypeptide not according to the invention), under comparable conditions. Preferably, the renal clearance rate of the conjugate is reduced by at least 50%, preferably by at least 75%, and most preferably by at least 90% compared to a relevant reference polypeptide.
Generally, activation of the receptor is coupled to receptor-mediated clearance (RMC) such that binding of a polypeptide to its receptor without activation does not lead to RMC, while activation of the receptor leads to RMC. The clearance is due to internalization of the receptor-bound polypeptide with subsequent lysosomal degradation. Reduced RMC may be achieved by designing the conjugate so as to be able to bind and activate a sufficient number of receptors to obtain optimal in vivo biological response and avoid activation of more receptors than required for obtaining such response. This may be reflected in reduced in vitro bioactivity and/or increased off-rate. In a preferred embodiment, the conjugates of the invention have a substantially reduced in vitro bioactivity compared to that of non-conjugated hG-CSF.
Typically, reduced in vitro bioactivity reflects reduced efficacy/efficiency and/or reduced potency and may be determined by any suitable method for determining any of these properties. For instance, in vitro bioactivity may be determined in a luciferase based assay (xe2x80x9cPrimary assay 2xe2x80x9d; see Materials and Methods). Another method for determining the in vitro bioactivity is to determine the binding affinity of a conjugate of the invention using the cell-based assay described in the Materials and Methods section (xe2x80x9cSecondary assayxe2x80x9d).
It has been found that a relatively low in vitro bioactivity, compared to the activity of hG-CSF (SEQ ID NO:1), is advantageous in terms of both a long plasma half-life and a high degree of stimulation of neutrophils. Surprisingly, it has been found that administration of G-CSF conjugates of the invention having a low in vitro bioactivity results in a faster neutrophil recovery, i.e. a faster recovery of the neutrophil count to a normal level, than administration of hG-CSF. Since it is critical to be able to reduce the duration of neutropenia as much as possible in patients having a reduced neutrophil level due to e.g. chemotherapy or radiation therapy, this is an important finding. Thus, in a preferred embodiment, the in vitro bioactivity of a conjugate of the invention is in the range of about 2-30%, preferably about 3-25%, of the bioactivity of hG-CSF (where the hG-CSF used as the reference polypeptide has SEQ ID NO:1, optionally with an N-terminal methionine residue; the reference hG-CSF may in particular be Neupogen(copyright), i.e. non-glycosylated Met-hG-CSF) as determined by the luciferase assay described herein, or, alternatively, using the cell-based receptor binding affinity assay (xe2x80x9cSecondary assayxe2x80x9d). The in vitro bioactivity of the conjugate is thus preferably reduced by at least 70%, such as by at least 75%, e.g. by at least 80% or 85%, as compared to the in vitro bioactivity of hG-CSF, determined under comparable conditions. Expressed differently, the conjugate may have an in vitro bioactivity that is as small as about 2%, typically at least about 3%, such as at least about 4% or 5%, of that of the wild-type polypeptide. For instance, the in vitro bioactivity may be in the range of about 4-20% of that of hG-CSF, determined under comparable conditions. In cases where reduced in vitro bioactivity is desired in order to reduce receptor-mediated clearance, it will be clear that sufficient bioactivity to obtain the desired receptor activation must nevertheless be maintained, which is why the bioactivity should be at least about 2% of that of hG-CSF and preferably slightly higher as explained above.
It has been found that amino acid alterations, in particular substitutions, in the helix regions of G-CSF, i.e. in an amino acid residue selected from amino acid position 11-41 (helix A), 71-95 (helix B), 102-125 (helix C), and 145-170 (helix D) (compared to SEQ ID NO:1), result in a reduced receptor-mediated clearance and thus an increased in vivo half-life when the resulting polypeptides are conjugated to polyethylene glycol. In addition to a longer half-life, it has surprisingly been found that administration of such polypeptide conjugates is able to stimulate production of white blood cells and neutrophils to the same degree as, or even better than, administration of the commercially available G-CSF products Neupogen(copyright) and Neulasta(trademark). G-CSF conjugates having a reduced in vitro bioactivity may thus be prepared by altering, typically by substitution, one or more amino acid residues in a helix region of G-CSF, and by conjugating the resulting polypeptide to one or more non-polypeptide moieties such as polyethylene glycol.
Preferably, the off-rate between the polypeptide conjugate and its receptor is increased by a magnitude resulting in the polypeptide conjugate being released from its receptor before any substantial internalization of the receptor-ligand complex has taken place. The receptor-polypeptide binding affinity may be determined as described in the Materials and Methods section herein. The off-rate may be determined using the Biacore(copyright) technology as described in the Materials and Methods section. The in vitro RMC may be determined by labeling (e.g. radioactive or fluorescent labeling) the polypeptide conjugate, stimulating cells comprising the receptor for the polypeptide, washing the cells, and measuring label activity. Alternatively, the conjugate may be exposed to cells expressing the relevant receptor. After an appropriate incubation time the supernatant is removed and transferred to a well containing similar cells. The biological response of these cells to the supernatant is determined relative to a non-conjugated polypeptide or another reference polypeptide, and this is a measure of the extent of the reduced RMC.
Normally, reduced in vitro bioactivity of the conjugate is obtained as a consequence of its modification by a non-polypeptide moiety. However, in order to further reduce in vitro bioactivity or for other reasons it may be of interest to modify the polypeptide part of the conjugate further. For instance, in one embodiment at least one amino acid residue located at or near a receptor binding site of the polypeptide may be substituted with another amino acid residue as compared to the corresponding wild-type polypeptide so as to obtain reduced in vitro bioactivity. The amino acid residue to be introduced by substitution may be any amino acid residue capable of reducing in vitro bioactivity of the conjugate. Conveniently, the introduced amino acid residue comprises an attachment group for the non-polypeptide moiety as defined herein. In particular, when the non-polypeptide moiety is a polymer molecule such as PEG molecule, the amino acid residue to be introduced may be a lysine residue.
The term xe2x80x9cexhibiting G-CSF activityxe2x80x9d is intended to indicate that the polypeptide or conjugate has one or more of the functions of native G-CSF, in particular hG-CSF with the amino acid sequence shown in SEQ ID NO:1, including the capability to bind to a G-CSF receptor (Fukunaga et al., J. Bio. Chem, 265:14008, 1990). The G-CSF activity is conveniently assayed using the primary assay described in the Materials and Methods section hereinafter. The polypeptide xe2x80x9cexhibitingxe2x80x9d G-CSF activity is considered to have such activity when it displays a measurable function, e.g. a measurable proliferative activity or a receptor binding activity (e.g. as determined by the primary assay described in the Materials and Methods section). The polypeptide exhibiting G-CSF activity may also be termed xe2x80x9cG-CSF moleculexe2x80x9d herein for the sake of simplicity, even though such polypeptides are in fact variants of G-CSF.
The term xe2x80x9cparent G-CSFxe2x80x9d or xe2x80x9cparent polypeptidexe2x80x9d is intended to indicate the molecule to be modified in accordance with the present invention. The parent G-CSF is normally hG-CSF or a variant thereof. A xe2x80x9cvariantxe2x80x9d is a polypeptide which differs in one or more amino acid residues from a parent polypeptide, normally in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 amino acid residues. Examples of rhG-CSF include filgrastim (Gran(copyright) and Neupogen(copyright)), lenograstim (Neutrogin(copyright) and Granocyte(copyright)) and nartograstim (Neu-up(copyright)).
Conjugate of the Invention
As stated above, in a first aspect the invention relates to a conjugate comprising a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence of SEQ ID NO:1 in at least one amino acid residue selected from specified introduced or removed amino acid residues comprising an attachment group for a non-polypeptide moiety, and at least one non-polypeptide moiety attached to an attachment group of the polypeptide. The amino acid residues to be introduced and/or removed are described in further detail in the following sections. It will be understood that the conjugate itself also exhibits G-CSF activity.
By removing and/or introducing an amino acid residue comprising an attachment group for the non-polypeptide moiety it is possible to specifically adapt the polypeptide so as to make the molecule more susceptible to conjugation to the non-polypeptide moiety of choice, to optimize the conjugation pattern (e.g. to ensure an optimal distribution of non-polypeptide moieties on the surface of the G-CSF molecule and to ensure that only the attachment groups intended to be conjugated are present in the molecule) and thereby obtain a new conjugate molecule which has G-CSF activity and in addition one or more improved properties as compared to G-CSF molecules available today.
While the polypeptide may be of any origin, in particular mammalian origin, it is presently preferred to be of human origin, in particular a variant of a polypeptide having the amino acid sequence of SEQ ID NO:1.
In preferred embodiments of the present invention more than one amino acid residue of the polypeptide with G-CSF activity is altered, e.g. the alteration embraces removal as well as introduction of amino acid residues comprising an attachment group for the non-polypeptide moiety of choice.
In addition to the amino acid alterations disclosed herein aimed at removing and/or introducing attachment sites for the non-polypeptide moiety, it will be understood that the amino acid sequence of the polypeptide of the invention may if desired contain other alterations that need not be related to introduction or removal of attachment sites, i.e. other substitutions, insertions or deletions. These may, for example, include truncation of the N- and/or C-terminus by one or more amino acid residues, or addition of one or more extra residues at the N- and/or C-terminus, e.g. addition of a methionine residue at the N-terminus.
The conjugate of the invention has one or more of the following improved properties as compared to hG-CSF, in particular as compared to rhG-CSF (e.g. filgrastim, lenograstim or nartograstim) or known hG-CSF variants: increased ability to reduce the duration of neutropenia, increased functional in vivo half-life, increased serum half-life, reduced renal clearance, reduced receptor-mediated clearance, reduced side effects such as bone pain, and reduced immunogenicity.
It will be understood that the amino acid residue comprising an attachment group for a non-polypeptide moiety, whether it be removed or introduced, will be selected on the basis of the nature of the non-polypeptide moiety of choice and, in most instances, on the basis of the method by which conjugation between the polypeptide and the non-polypeptide moiety is to be achieved. For instance, when the non-polypeptide moiety is a polymer molecule such as a polyethylene glycol or polyalkylene oxide derived molecule amino acid residues comprising an attachment group may be selected from the group consisting of lysine, cysteine, aspartic acid, glutamic acid, histidine and arginine. When conjugation to a lysine residue is to be achieved, a suitable activated molecule is e.g. mPEG-SPA from Shearwater Corp., oxycarbonyl-oxy-N-dicarboxyimide-PEG (U.S. Pat. No. 5,122,614), or PEG available from PolyMASC Pharmaceuticals plc. The first of these will be illustrated further below.
In order to avoid too much disruption of the structure and function of the parent hG-CSF molecule, the total number of amino acid residues to be altered in accordance with the present invention, e.g. as described in the subsequent sections herein, (as compared to the amino acid sequence shown in SEQ ID NO:1) will typically not exceed 15. The exact number of amino acid residues and the type of amino acid residues to be introduced or removed depends in particular on the desired nature and degree of conjugation (e.g. the identity of the non-polypeptide moiety, how many non-polypeptide moieties it is desirable or possible to conjugate to the polypeptide, where conjugation is desired or should be avoided, etc.). Preferably, the polypeptide part of the conjugate of the invention or the polypeptide of the invention comprises an amino acid sequence which differs in 1-15 amino acid residues from the amino acid sequence shown in SEQ ID NO:1, typically in 2-10 amino acid residues, e.g. in 3-8 amino acid residues, such as 4-6 amino acid residues, from the amino acid sequence shown in SEQ ID NO:1. Thus, normally the polypeptide part of the conjugate or the polypeptide of the invention comprises an amino acid sequence which differs from the amino acid sequence shown in SEQ ID NO:1 in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 amino acid residues.
The polypeptide part of the conjugate will typically have an amino acid sequence with at least about 80% identity with SEQ ID NO:1, preferably at least about 90%, such as at least about 95%, e.g. at least about 96%, 97%, 98% or 99% sequence identity with SEQ ID is NO:1. Amino acid sequence homology/identity is conveniently determined from aligned sequences, using e.g. the ClustalW program, version 1.8, June 1999, using default parameters (Thompson et al., 1994, ClustalW: Improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice, Nucleic Acids Research, 22: 4673-4680) or from the PFAM families database version 4.0 (http://pfam.wustl.edu/) (Nucleic Acids Res. 1999 Jan 1; 27(1):260-2) by use of GENEDOC version 2.5 (Nicholas, K. B., Nicholas H. B. Jr., and Deerfield, D. W. II. 1997 GeneDoc: Analysis and Visualization of Genetic Variation, EMBNEW.NEWS 4:14; Nicholas, K. B. and Nicholas H. B. Jr. 1997 GeneDoc: Analysis and Visualization of Genetic Variation).
In a preferred embodiment one difference between the amino acid sequence of the polypeptide and the amino acid sequence shown in SEQ ID NO:1 is that at least one and often more, e.g. 1-15, amino acid residues comprising an attachment group for the non-polypeptide moiety has been introduced, preferably by substitution, into the amino acid sequence. Thereby, the polypeptide part is altered in the content of the specific amino acid residues to which the non-polypeptide moiety of choice binds, whereby a more efficient, specific and/or extensive conjugation is achieved. For instance, when the total number of amino acid residues comprising an attachment group for the non-polypeptide of choice is altered to an optimized level, the clearance of the conjugate is typically significantly reduced, due to the altered shape, size and/or charge of the molecule achieved by the conjugation. Furthermore, when the total number of amino acid residues comprising an attachment group for the non-polypeptide of choice is increased, a greater proportion of the polypeptide molecule is shielded by the non-polypeptide moieties of choice, leading to a lower immune response.
The term xe2x80x9cone differencexe2x80x9d as used in the present application is intended to allow for additional differences being present. Accordingly, in addition to the specified amino acid difference, other amino acid residues than those specified may be mutated.
In a further preferred embodiment one difference between the amino acid sequence of the polypeptide and the amino acid sequence shown in SEQ ID NO:1 is that at least one and preferably more, e.g. 1-15, amino acid residues comprising an attachment group for the non-polypeptide moiety has/have been removed, preferably by substitution, from the amino acid sequence. By removing one or more amino acid residues comprising an attachment group for the non-polypeptide moiety of choice it is possible to avoid conjugation to the non-polypeptide moiety in parts of the polypeptide in which such conjugation is disadvantageous, e.g. in amino acid residues located at or near a functional site of the polypeptide (since conjugation at such a site may result in inactivation or reduced G-CSF activity of the resulting conjugate due to impaired receptor recognition). In the present context the term xe2x80x9cfunctional sitexe2x80x9d is intended to indicate one or more amino acid residues which is/are essential for or otherwise involved in the function or performance of hG-CSF. Such amino acid residues are a part of the functional site. The functional site may be determined by methods known in the art and is preferably identified by analysis of a structure of the polypeptide complexed to a relevant receptor, such as the hG-CSF receptor (See Aritomi et al. Nature 401:713-717, 1999).
In a still further preferred embodiment, the amino acid sequence of the polypeptide differs from the amino acid sequence shown in SEQ ID NO:1 in that a) at least one specified amino acid residue comprising an attachment group for the non-polypeptide moiety and present in the amino acid sequence shown in SEQ ID NO:1 has been removed, preferably by substitution, and b) at least one specified amino acid residue comprising an attachment group for the non-polypeptide moiety has been introduced into the amino acid sequence, preferably by substitution, the specified amino acid residues being any of those described in the subsequent sections herein. This embodiment is considered of particular interest in that it is possible to specifically design the polypeptide so as to obtain an optimal conjugation to the non-polypeptide moiety of choice. For instance, by introducing and removing selected amino acid residues as disclosed in the following sections it is possible to ensure an optimal distribution of attachment groups for the non-polypeptide moiety of choice, which gives rise to a conjugate in which the non-polypeptide moieties are placed so as to a) effectively shield epitopes and other surface parts of the polypeptide and b) ensure an optimal Stokes radius of the conjugate, without causing too much structural disruption and thereby impair the function of the polypeptide.
The conjugate of the invention will in general comprise a sufficient number and type of non-polypeptide moieties to provide the conjugate with an increased functional in vivo half-life and/or serum half-life as compared to hG-CSF, e.g. filgrastim, lenograstim or nartograstim, and preferably as compared to rhG-CSF comprising a single N-terminally attached 20 kDa PEG moiety. The increased functional in vivo half-life is conveniently determined as described in the Materials and Methods section herein.
The conjugate of the invention may comprise at least one non-conjugated, conjugatable attachment group for the non-polypeptide moiety. In the present context the term xe2x80x9cconjugatable attachment groupxe2x80x9d is intended to indicate an attachment group that is located in a position of the polypeptide where it is accessible for conjugation, and that but for special precautions is conjugated to the relevant non-polypeptide moiety when subjected to conjugation. For instance, such attachment group may be part of an amino acid residue involved in or otherwise essential for the polypeptide to exert its activity. A convenient way to avoid conjugation of an otherwise conjugatable attachment group is to shield the attachment group by means of a helper molecule, e.g. as described in the section entitled xe2x80x9cBlocking of the functional sitexe2x80x9d. It will be understood that the number of non-conjugated, conjugatable attachment groups depends on the specific G-SCF polypeptide and the location of the conjugatable attachment groups. For instance, the polypeptide conjugate comprises one or two non-conjugated, conjugatable attachment groups, and at least one, and preferably two or more conjugated attachment groups.
The four helices of G-CSF comprise amino acid residues 11-41 (helix A), 71-95 (helix B), 102-125 (helix C), and 145-170 (helix D) (Zink et al. (1994) Biochemistry 33: 8453-8463). Surprisingly, it has been found that advantageous results may be obtained when non-polypeptide moieties are attached to amino acid residues located in one or more of the helices of G-CSF, even though modification of protein helices, e.g. the helix structures of four-helix bundle proteins such as G-CSF, is generally considered to be accompanied by a risk of disturbance of protein function. In one embodiment, the polypeptide conjugate of the invention therefore comprises at least one non-polypeptide moiety attached to an attachment group of an amino acid residue located in one of the four helices, in particular in one or more of the B, C or D helices
Conjugate of the Invention, Wherein the Non-polypeptide Moiety is Attached to a Lysine or the N-terminal Amino Acid Residue
In one aspect the invention relates to a polypeptide conjugate comprising
i) a polypeptide exhibiting G-CSF activity, comprising an amino acid sequence that differs from the amino acid sequence shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of T1K, P2K, L3K, G4K, P5K, A6K, S7K, S8K, L9K, P10K, Q11K, S12K, F13K, L14K, L15K, E19K, Q20K, V21K, Q25K, G26K, D27K, A29K, A30K, E33K, A37K, T38K, Y39K, L41K, H43K, P44K, E45K, E46K, V48K, L49K, L50K, H52K, S53K, L54K, 156K, P57K, P60K, L61K, S62K, S63K, P65K, S66K, Q67K, A68K, L69K, Q70K, L71K, A72K, G73K, S76K, Q77K, L78K, S80K, F83K, Q86K, G87K, Q90K, E93K, G94K, S96K, P97K, E98K, L99K, G100K, P101K, T102K, D104K, T105K, Q107K, L108K, D109K, A111K, D112K, F113K, T115K, T116K, W118K, Q119K, Q120K, M121K, E122K, E123K, L124K, M126K, A127K, P128K, A129K, L130K, Q131K, P132K, T133K, Q134K, G135K, A136K, M137K, P138K, A139K, A141K, S142K, A143K, F144K, Q145K, S155K, H156K, Q158K, S159K, L161K, E162K, V163K, S164K, Y165K, V167K, L168K, H170K, L171K, A172K, Q173K and P174K, and
ii) at least one non-polypeptide moiety attached to a lysine residue of the polypeptide.
hG-CSF contains four lysine residues, of which K16 is located in the receptor-binding domain and the others are located in positions 23, 34 and 40, respectively, all relatively close to the receptor-binding domain. In order to avoid conjugation to one or more of these lysine residues (since this may inactivate or severely reduce the activity of the resulting conjugate) it may be desirable to remove at least one lysine residue, e.g. two, three or all of these residues. Accordingly, in another, more preferred aspect the invention relates to a polypeptide conjugate as defined above, wherein at least one of the amino acid residues selected from the group consisting of K16, K23, K34 and K40 has been deleted or substituted with another amino acid Q90K, T105K, Q120K, T133K, S159K and H170K/Q/R, such as two, three, four or five of these substitutions, for example: Q70K+Q90K, Q70K+T105K, Q70K+Q120K, Q70K+T133K, Q70K+S159K, Q70K+H170K, Q90K+T105K, Q90K+Q120K, Q90K+T133K, Q90K+S159K, Q90K+H170K, T105K+Q120K, T105K+T133K, T105K+S159K, T105K+H170K, Q120K+T133K, Q120K+S159K, Q120K+H170K, T133K+S159K, T133K+H170K, S159K+H170K, Q70K+Q90K+T105K, Q70K+Q90K+Q120K, Q70K+Q90K+T133K, Q70K+Q90K+S159K, Q70K+Q90K+H170K, Q70K+T105K+Q120K, Q70K+T105K+T133K, Q70K+T105K+S159K, Q70K+T105K+H170K, Q70K+Q120K+T133K, Q70K+Q120K+S159K, Q70K+Q120K+H170K, Q70K+T133K+S159K, Q70K+T133K+H170K, Q70K+S159K+H170K, Q90K+T105K+Q120K, Q90K+T105K+T133K, Q90K+T105K+S159K, Q90K+T105K+H170K, Q90K+Q120K+T133K, Q90K+Q120K+S159K, Q90K+Q120K+H170K, Q90K+T133K+S159K, Q90K+T133K+H170K, Q90+S159K+H170K, T105K+Q120K+T133K, T105K+Q120K+S159K, T105K+Q120K+H170K, T105K+T133K+S159K, T105K+T133K+H170K, T105K+S159K+H170K, Q120K+T133K+S159K, Q120K+T133K+H170K, Q120K+S159K+H170K, T133K+S159K+H170K, Q70K+Q90K+T105K+Q120K, Q70K+Q90K+T105K+T133K, Q70K+Q90K+T105K+S159K, Q70K+Q90K+T105K+H170K, Q70K+Q90K+Q120K+T133K, Q70K+Q90K+Q120K+S159K, Q70K+Q90K+Q120K+H170K, Q70K+Q90K+T133K+S159K, Q70K+Q90K+T133K+H170K, Q70K+Q90K+S159K+H170K, Q70K+T105K+Q120K+T133K, Q70K+T105K+Q120K+S159K, Q70K+T105K+Q120K+H170K, Q70K+T105K+T133K+S159K, Q70K+T105K+T133K+H170K, Q70K+T105K+S159K+H170K, Q70K+Q120K+T133K+S159K, Q70K+Q120K+T133K+H170K, Q70K+T133K+S159K+H170K, Q90K+T105K+Q120K+T133K, Q90K+T105K+Q120K+S159K, Q90K+T105K+Q120K+H170K, Q90K+T105+T133K+S159K, Q90K+T105+T133K+H107K, Q90K+T105+S159K+H170K, Q90K+Q120K+T133K+S159K, Q90K+Q120K+T133K+H170K, Q90K+Q120K+S159K+H170K, Q90K+T133K+S159K+H170K, T105K+Q120K+T133K+S159K, T105K+Q120K+T133K+H170K, T105K+Q120K+S159K+H170K, T105K+T133K+S159K+H170K or Q120K+T133K+S159K+H170K. In any of the variants listed above, the substitution H170K may instead be HI 70Q or H170R.
The polypeptide of the conjugate according to this aspect of the invention, i.e. having at least one introduced and one removed lysine, preferably comprises at least one, such as one, two, three or four, of the substitutions selected from the group consisting of K16R, K16Q, K23R, K23Q, K34R, K34Q, K40R and K40Q, preferably at least the substitution K16R, whereby conjugation of this residue can be avoided. Preferably, the polypeptide comprises at least one substitution selected from the group consisting of K16R+K23R, K16R+K34R, K16R+K40R, K23R+K34R, K23R+K40R, K34R+K40R, K16R+K23R+K34R, K16R+K23R+K40R, K23R+K34R+K40R, K16R+K34R+K40R and K16R+K23R+K34R+K40R. In one preferred embodiment, the polypeptide includes the substitutions K16R+K34R+K40R, while the lysine in position 23 is left unaltered. As indicated above, it is contemplated that any of the individual substitutions or combinations listed in this paragraph for removal of a lysine residue may suitably be used with any of the other substitutions disclosed herein for introduction of lysine residues, in particular the substitutions listed in the paragraph above.
In a particular embodiment the polypeptide includes the substitutions K16R, K34R, K40R, T105K and S159K and is conjugated to 2-6, typically 3-6 polyethylene glycol moieties with a molecular weight of about 1000-10,000 Da.
In one embodiment the conjugate of the invention has a glycosylation in T133, i.e. this position is unaltered from the wild-type hG-CSF. This is the natural glycosylation site. Alternatively, the conjugate may be non-glycosylated, although glycosylated conjugates are preferred.
In particular, the conjugate may have 2-6, typically 3-6 polyethylene glycol moieties with a molecular weight of about 5000-6000 Da attached, e.g. mPEG with a molecular weight of about 5 kDa. Preferably, the conjugate has 4-5 polyethylene glycol moieties with a molecular weight of about 5000-6000 Da attached, e.g. 5 kDa mPEG.
In another embodiment, the conjugate may be produced so as to have only a single number of PEG moieties attached, e.g. either 2, 3, 4, 5 or 6 PEG moieties per polypeptide, or to have a desired mix of polypeptide conjugates with different numbers of PEG moieties attached, e.g. a mix having 2-5, 2-4, 3-5, 3-4, 4-6, 4-5 or 5-6 attached PEG moieties. As indicated ab an example of a preferred conjugate mix is one having 4-5 PEG moieties of about 5 kDa.
It will be understood that a conjugate having a specific number of attached PEG moieties, or a mix of conjugates having a defined range of numbers of attached PEG moieties, may be obtained by choosing suitable PEGylation conditions and optionally by using subsequent purification to separate conjugates having the desired number of PEG moieties. Examples of methods for separation of G-CSF molecules with different numbers of PEG moieties attached are provided below. Determination of the number of attached PEG moieties may e.g. be performed using SDS-PAGE. For purposes of the present invention, a polypeptide conjugate may be considered to have a given number of attached PEG moieties if separation on an SDS-PAGE gel shows no or only insignificant bands other than the band(s) corresponding to the given number(s) of PEG moieties. For example, a sample of a polypeptide conjugate is considered to have 4-5 attached PEG groups if an SDS-PAGE gel on which the sample has been run shows bands corresponding to 4 and 5 PEG groups, respectively, and only insignificant bands or, preferably, no bands corresponding to 3 or 6 PEG groups.
While the non-polypeptide moiety of the conjugate according to this aspect of the invention may be any molecule which, when using the given conjugation method has lysine as an attachment group such as a carbohydrate moiety, it is preferred that the non-polypeptide moiety is a polymer molecule. The polymer molecule may be any of the molecules mentioned in the section entitled xe2x80x9cConjugation to a polymer moleculexe2x80x9d, but is preferably selected from the group consisting of linear or branched polyethylene glycol or another polyalkylene oxide. Preferred polymer molecules are e.g. mPEG-SPA (in particular SPA-mPEG 5000) from Shearwater Corp. or oxycarbonyl-oxy-N-dicarboxyimide PEG (U.S. Pat. No. 5,122,614).
It will be understood that any of the amino acid changes, in particular substitutions, specified in this section can be combined with any of the amino acid changes, preferably substitutions, specified in the other sections herein disclosing specific amino acid modifications, including introduction and/or removal of glycosylation sites.
Conjugate of the Invention, Wherein the Non-polypeptide Moiety is a Molecule which has Cysteine as an Attachment Group
In another aspect the invention relates to a conjugate comprising
i) a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence of hG-CSF shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of T1C, P2C, L3C, G4C, P5C, A6C, S7C, S8C, L9C, P10C, Q11C, S12C, F13C, L14C, L15C, E19C, Q20C, V21C, R22C, Q25C, G26C, D27C, A29C, A30C, E33C, A37C, T38C, Y39C, L41C, H43C, P44C, E45C, E46C, V48C, L49C, L50C, H52C, S53C, L54C, I56C, P57C, P60C, L61C, S62C, S63C, P65C, S66C, Q67C, A68C, L69C, Q70C, L71C, A72C, G73C, S76C, Q77C, L78C, S80C, F83C, Q86C, G87C, Q90C, E93C, G94C, S96C, P97C, E98C, L99C, G100C, P101C, T102C, D104C, T105C, Q107C, L108C, D109C, A111C, D112C, F113C, T115C, T116C, W118C, Q119C, Q120C, M121C, E122C, E123C, L124C, M126C, A127C, P128C, A129C, L130C, Q131C, P132C, T133C, Q134C, G135C, A136C, M137C, P138C, A139C, A141C, S142C, A143C, F144C, Q145C, R146C, R147C, S155C, H156C, Q158C, S159C, L161C, E162C, V163C, S164C, Y165C, R166C, V167C, L168C, R169C, H170C, L171C, A172C, Q173C and P174C, and
ii) at least one non-polypeptide moiety attached to a cysteine residue of the polypeptide.
The receptor-binding domain of hG-CSF contains a cysteine residue in position 17 which does not take part in a cystine and which may advantageously be removed in order to avoid conjugation of a non-polypeptide moiety to said cysteine. Accordingly, in another, more preferred aspect the invention relates to a conjugate comprising
i) a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of T1C, P2C, L3C, G4C, P5C, A6C, S7C, S8C, L9C, P10C, Q11C, S12C, F13C, L14C, L15C, E19C, Q20C, V21C, R22C, Q25C, G26C, D27C, A29C, A30C, E33C, A37C, T38C, Y39C, L41C, H43C, P44C, E45C, E46C, V48C, L49C, L50C, H52C, S53C, L54C, 156C, P57C, P60C, L61C, S62C, S63C, P65C, S66C, Q67C, A68C, L69C, Q70C, L71C, A72C, G73C, S76C, Q77C, L78C, S80C, F83C, Q86C, G87C, Q90C, E93C, G94C, S96C, P97C, E98C, L99C, G100C, P101C, T102C, D104C, T105C, Q107C, L108C, D109C, A111C, D112C, F113C, T115C, T116C, W118C, Q119C, Q120C, M121C, E122C, E123C, L124C, M126C, A127C, P128C, A129C, L130C, Q131C, P132C, T133C, Q134C, G135C, A136C, M137C, P138C, A139C, A141C, S142C, A143C, F144C, Q145C, R146C, R147C, S155C, H156C, Q158C, S159C, L161C, E162C, V163C, S164C, Y165C, R166C, V167C, L168C, R169C, H170C, L171C, A172C, Q173C and P174C, in combination with removal of C17, preferably substitution of C17 with any other amino acid residue, e.g. with a serine residue, and
ii) a non-polypeptide moiety which has a cysteine residue as an attachment group.
Preferred substitutions according to this aspect of the invention are substitutions of arginine with cysteine, for example one or more of R146C, R147C, R166C and R169C.
It will be understood that any of the amino acid modifications, in particular substitutions, specified in this section can be combined with any of the amino acid changes, in particular substitutions, specified in the other sections herein disclosing specific amino acid modifications, including introduction and/or removal of glycosylation sites.
Conjugate of the Invention Wherein the Non-polypeptide Moiety Binds to an Acid Group or the C-terminal Amino Acid Residue
In a still further aspect the invention relates to a conjugate comprising
i) a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of T1D, P2D, L3D, G4D, P5D, A6D, S7D, S8D, L9D, P10D, Q11D, S12D, F13D, L14D, L15D, K16D, Q20D, V21D, R22D, K23D, Q25D, G26D, A29D, A30D, K34D, A37D, T38D, Y39D, K40D, L41D, H43D, P44D, V48D, L49D, L50D, H52D, S53D, L54D, 156D, P57D, P60D, L61D, S62D, S63D, P65D, S66D, Q67D, A68D, L69D, Q70D, L71D, A72D, G73D, S76D, Q77D, L78D, S80D, F83D, Q86D, G87D, Q90D, G94D, S96D, P97D, L99D, G100D, P101D, T102D, T105D, Q107D, L108D, A111D, F113D, T115D, T116D, W118D, Q119D, Q120D, M121D, L124D, M126D, A127D, P128D, A129D, L130D, Q131D, P132D, T133D, Q134D, G135D, A136D, M137D, P138D, A139D, A141D, S142D, A143D, F144D, Q145D, R146D, R147D, S155D, H156D, Q158D, S159D, L161D, V163D, S164D, Y165D, R166D, V167D, L168D, R169D, H170D, L171D, A172D, Q173D and P174D; or at least one substitution selected from the group consisting of T1E, P2E, L3E, G4E, P5E, A6E, S7E, S8E, L9E, P10E, Q11E, S12E, F13E, L14E, L15E, K16E, Q20E, V21E, R22E, K23E, Q25E, G26E, A29E, A30E, K34E, A37E, T38E, Y39E, K40E, L41E, H43E, P44E, V48E, L49E, L50E, H52E, S53E, L54E, 156E, P57E, P60E, L61E, S62E, S63E, P65E, S66E, Q67E, A68E, L69E, Q70E, L71E, A72E, G73E, S76E, Q77E, L78E, S80E, F83E, Q86E, G87E, Q90E, G94E, S96E, P97E, L99E, G100E, P101E, T102E, T105E, Q107E, L108E, A111E, F113E, T115E, T116E, W118E, Q119E, Q120E, M121E, L124E, M126E, A127E, P128E, A129E, L130E, Q131E, P132E, T133E, Q134E, G135E, A136E, M137E, P138E, A139E, A141E, S142E, A143E, F144E, Q145E, R146E, R147E, S155E, H156E, Q158E, S159E, L161E, V163E, S164E, Y165E, R166E, V167E, L168E, R169E, H170E, L171E, A172E, Q173E and P174E; and
ii) a non-polypeptide moiety having an aspartic acid or a glutamic acid residue as an attachment group.
Examples of preferred substitutions according to this aspect of the invention include Q67D/E, Q70D/E, Q77D/E, Q86D/E, Q90D/E, Q120D/E, Q131D/E, Q134D/E, Q145D/E and Q173D/E.
In addition to the above listed substitutions, the polypeptide of the conjugate according to any of the above aspects may comprise removal, preferably by substitution, of at least one of the amino acid residues selected from the group consisting of D27, D104, D109, DI 12, E19, E33, E45, E46, E93, E98, E122, E123, and E163. The substitution may be for any other amino acid residue, in particular for an asparagine or a glutamine residue, whereby conjugation of these residues can be avoided. In particular, the polypeptide may comprise at least one of the following substitutions: D27N, D104N, D109N, D112N, E19Q, E33Q, E45Q, E46Q, E93Q, E98Q, E122Q, E123Q and E163Q. Preferably, the amino acid substitution in one or more of the above positions may in addition be combined with at least one of the following substitutions: D109N, D112N, E19Q, E122Q and E123Q.
While the non-polypeptide moiety of the conjugate according to this aspect of the invention, which has an acid group as an attachment group, can be any non-polypeptide moiety with such property, it is presently preferred that the non-polypeptide moiety is a polymer molecule or an organic derivatizing agent, in particular a polymer molecule, and the conjugate is prepared e.g. as described by Sakane and Pardridge, Pharmaceutical Research, Vol. 14, No. 8, 1997, pp 1085-1091.
It will be understood that any of the amino acid changes, in particular substitutions, specified in this section can be combined with any of the amino acid changes, in particular substitutions specified in the other sections herein disclosing specific amino acid changes, including introduction and/or removal of glycosylation sites.
Other Conjugates of the Invention
In addition to the non-polypeptide moieties specified above e.g. in the sections entitled xe2x80x9cConjugate of the invention . . . xe2x80x9d the conjugate of the invention may contain one or more carbohydrate moieties as a consequence of the polypeptide being expressed in a glycosylating host cell to result in glycosylation at the natural glycosylation site of hG-CSF (T133) and/or at introduced glycosylation site(s).
Conjugate of the Invention Wherein the Non-polypeptide Moiety is a Carbohydrate Moiety
In a further aspect the invention relates to a conjugate comprising a glycosylated polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from that shown in SEQ ID NO:1 in that at least one non-naturally occurring glycosylation site has been introduced into the amino acid sequence by way of at least one substitution selected from the group consisting of L3N+P5S/T, P5N, A6N, S8N+P10S/T, P10N, Q11N+F13S/T, S12N+L14S/T, F13N+L15S/T, L14N+K16S/T, K16N+L18S/T, E19N+V21S/T, Q20N+R22/T, V21N+K23S/T, R22N+124S/T, K23N+Q25S/T, Q25N+D27S/T, G26N+G28S/T, D27N+A29S/T, A29N+L31S/T, A30N+Q32S/T, E33N+L35S/T, A37N+Y39S/T, T38N+K40S/T, Y39N+L41S/T, P44N+E46S/T, E45N+L47S/T, E46N+V48S/T, V48N+L50S/T, L49N+G51S/T, L50N+H52S/T, H52N+L54S/T, S53N+G55S/T, P60N, L61N, S63N+P65S/T, P65N+Q67S/T, S66N+A68S/T, Q67N+L69S/T, A68N+Q70S/T, L69N+L71S/T, Q70N+A72S/T, L71N+G73S/T, G73N+L75S/T, S76N+L78S/T, Q77N+H79S/T, L78N, S80N+L82S/T, F83N+Y85S/T, Q86N+L88S/T, G87N+L89S/T, Q90N+L92S/T, E93N+I95S/T, P97N+L99S/T, L99N+P101S/T, P101N+L103S/T, T102N+D104S/T, D104N+L106S/T, T105N+Q107S/T, Q107N+D109S/T, L108N+V110S/T, D109N+A111S/T, A111N+F113S/T, D112N+A114S/T, F113N, T115N+I117S/T, T116N+W118S/T, W118N+Q120S/T, Q119N+M121S/T, Q120N+E122S/T, M121N+E123S/T, E122N+L124S/T, E123N+G125S/T, L124N+M126S/T, M126N+P128S/T, P128N+L130S/T, L130N+P132S/T, P132N+Q134S/T, T133N+G135S/T, Q134N+A136S/T, A136N+P138S/T, P138N+F140S/T, A139N+A141S/T, A141N+A143S/T, S142N+F144S/T, A143N+Q145S/T, F144N+R146S/T, Q145N+R147S/T, R146N+A148S/T, R147N+G149S/T, S155N+L157S/T, H156N+Q158S/T, S159N+L161S/T, L161N+V163S/T, E162N, V163N+Y165S/T, S164N+R166S/T, Y165N+V167S/T, R166N+L168S/T, V167N+R169S/T, L168N+H170S/T, R169N+L171S/T and H170N+A172S/T, wherein S/T indicates an S or a T residue, preferably a T residue.
It will be understood that in order to prepare a conjugate according to this aspect the polypeptide must be expressed in a glycosylating host cell capable of attaching oligosaccharide moieties at the glycosylation site(s) or alternatively subjected to in vitro glycosylation. Examples of glycosylating host cells are given in the section further below entitled xe2x80x9cCoupling to an oligosaccharide moietyxe2x80x9d.
Alternatively, the conjugate according to this aspect comprises a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from that shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of P5N, A6N, P10N, P60N, L61N, L78N, F113N and E162N, in particular from the group consisting of P5N, A6N, P10N, P60N, L61N, F113N and E162N, such as from the group consisting of P60N, L61N, F113N and E162N.
Alternatively, the conjugate according to this aspect comprises a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from that shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of D27N+A29S, D27N+A29T, D104N+L106S, D104N+L106T, D109N+A111S, D109N+A111T, D112N+A114S and D112N+A114T, more preferably from the group consisting of D27N+A29S, D27N+A29T, D104N+L106S, D104N+L106T, D112N+A114S and D112N+A114T, such as from the group consisting of D27N+A29S, D27N+A29T, D104N+L106S and D104N+L106T.
In addition to a carbohydrate molecule, the conjugate according to the aspect of the invention described in the present section may contain additional non-polypeptide moieties, in particular a polymer molecule, as described in the present application, conjugated to one or more attachment groups present in the polypeptide part of the conjugate.
It will be understood that any of the amino acid changes, in particular substitutions, specified in this section can be combined with any of the amino acid changes, in particular substitutions, specified in the other sections herein disclosing specific amino acid changes.
Circularly Permuted Variants
In a further embodiment, the polypeptide part of the polypeptide conjugate of the invention may be in the form of a circularly permuted variant of a polypeptide sequence otherwise disclosed herein. In such a circularly permuted polypeptide, the original N-terminus and C-terminus are joined together either directly by a peptide bond or indirectly via a peptide linker, while new N- and C-termini are formed between two adjacent amino acid residues that originally were joined by a peptide bond. Since the original N- and C-termini will normally be located at some distance from each other, they will typically be linked by means of a peptide linker having a suitable length and composition so that the structure and activity of the conjugate is not adversely affected. It will be clear that the new N-terminus and C-terminus should not be formed between an amino acid residue pair where this would interfere with the activity of the polypeptide. Circularly permuted G-CSF receptor agonists are disclosed in U.S. Pat. No. 6,100,070, to which reference is made for further information on selecting peptide linkers and the location of the new N-terminus and C-terminus as well as methods for producing them such variants.
White Blood Cell and Neutrophil Formation of Conjugates of the Invention
In a further embodiment, the polypeptide conjugate of the invention may be characterized as being a conjugate exhibiting G-CSF activity and comprising a polypeptide with an amino acid sequence that differs in at least one amino acid residue from the amino acid sequence shown in SEQ ID NO:1 and having at least one non-polypeptide moiety attached to an attachment group of the polypeptide, the polypeptide conjugate further fulfilling at least one of the following criteria (A)-(D):
(A) after one subcutaneous administration of 100 microgram per kg body weight to rats (based on the weight of the polypeptide part of the conjugate) it:
i) increases formation of white blood cells with at least about the same rate and to at least about the same level (measured as number of cells per liter of blood) as administration of 100 microgram of non-conjugated hG-CSF per kg body weight for a period of 6 hours, preferably 12 hours after administration, and
ii) increases the level of white blood cells (measured as number of cells per liter blood) above the level of white blood cells prior to administration for a period of at least about 96 hours, preferably for at least about 120 hours;
(B) after one subcutaneous administration of 25 microgram per kg body weight to rats (based on the weight of the polypeptide part of the conjugate) it:
i) increases formation of white blood cells with at least about the same rate and to at least about the same level (measured as number of cells per liter of blood) as administration of 100 microgram of non-conjugated hG-CSF per kg body weight for a period of 6 hours, preferably 12 hours after administration, and
ii) increases the level of white blood cells (measured as number of cells per liter blood) above the level of white blood cells prior to administration for a period of at least about 72 hours, preferably at least about 96 hours, more preferably at least about 120 hours;
(C) after one subcutaneous administration of 100 microgram per kg body weight to rats (based on the weight of the polypeptide part of the conjugate) it:
i) increases formation of neutrophils with at least about the same rate and to at least about the same level (measured as number of cells per liter of blood) as administration of 100 microgram of non-conjugated hG-CSF per kg body weight for a period of 6 hours, preferably 12 hours after administration, and
ii) increases the level of neutrophils (measured as number of cells per liter blood) above the level of neutrophils prior to administration for a period of at least about 96 hours, preferably at least about 120 hours;
(D) after one subcutaneous administration of 25 microgram per kg body weight to rats (based on the weight of the polypeptide part of the conjugate) it:
i) increases formation of neutrophils with at least about the same rate and to at least about the same level (measured as number of cells per liter of blood) as administration of 100 microgram of non-conjugated hG-CSF per kg body weight for a period of 6 hours, preferably 12 hours after administration, and
ii) increases the level of neutrophils (measured as number of cells per liter blood) above the level of neutrophils prior to administration for a period of at least about 72 hours, preferably at least about 96 hours, more preferably at least about 120 hours.
Non-polypeptide Moiety of the Conjugate of the Invention
As indicated further above the non-polypeptide moiety of the conjugate of the invention is preferably selected from the group consisting of a polymer molecule, a lipophilic compound, a carbohydrate moiety (e.g. by way of in vivo glycosylation) and an organic derivatizing agent. All of these agents may confer desirable properties to the polypeptide part of the conjugate, in particular increased functional in vivo half-life and/or increased serum half-life. The polypeptide part of the conjugate is normally conjugated to only one type of non-polypeptide moiety, but may also be conjugated to two or more different types of non-polypeptide moieties, e.g. to a polymer molecule and an oligosaccharide moiety, to a lipophilic group and an oligosaccharide moiety, to an organic derivatizing agent and an oligosaccharide moiety, to a lipophilic group and a polymer molecule, etc. The conjugation to two or more different non-polypeptide moieties may be done simultaneously or sequentially.
Methods for Preparing a Conjugate of the Invention
In the following sections xe2x80x9cConjugation to a lipophilic compoundxe2x80x9d, xe2x80x9cConjugation to a polymer moleculexe2x80x9d, xe2x80x9cConjugation to an oligosaccharide moietyxe2x80x9d and xe2x80x9cConjugation to an organic derivatizing agentxe2x80x9d conjugation to specific types of non-polypeptide moieties is described. In general, a polypeptide conjugate according to the invention may be produced by culturing an appropriate host cell under conditions conducive for expression of the polypeptide, and recovering the polypeptide, wherein a) the polypeptide comprises at least one N- or O-glycosylation site and the host cell is a eukaryotic host cell capable of in vivo glycosylation, and/or b) the polypeptide is subjected to conjugation to a non-polypeptide moiety in vitro.
Conjugation to a Lipophilic Compound
The polypeptide and the lipophilic compound may be conjugated to each other, either directly or by use of a linker. The lipophilic compound may be a natural compound such as a saturated or unsaturated fatty acid, a fatty acid diketone, a terpene, a prostaglandin, a vitamin, a carotenoid or steroid, or a synthetic compound such as a carbon acid, an alcohol, an amine and sulphonic acid with one or more alkyl, aryl, alkenyl or other multiple unsaturated compounds. The conjugation between the polypeptide and the lipophilic compound, optionally through a linker, may be done according to methods known in the art, e.g. as described by Bodanszky in Peptide Synthesis, John Wiley, New York, 1976 and in WO 96/12505.
Conjugation to a Polymer Molecule
The polymer molecule to be coupled to the polypeptide may be any suitable polymer molecule, such as a natural or synthetic homo-polymer or heteropolymer, typically with a molecular weight in the range of about 300-100,000 Da, such as about 500-20,000 Da, more preferably in the range of about 1000-15,000 Da, even more preferably in the range of about 2000-12,000 Da, such as about 3000-10,000. When used about polymer molecules herein, the word xe2x80x9caboutxe2x80x9d indicates an approximate average molecular weight and reflects the fact that there will normally be a certain molecular weight distribution in a given polymer preparation.
Examples of homo-polymers include a polyol (i.e. poly-OH), a polyamine (i.e. poly-NH2) and a polycarboxylic acid (i.e. poly-COOH). A hetero-polymer is a polymer which comprises different coupling groups, such as a hydroxyl group and an amine group.
Examples of suitable polymer molecules include polymer molecules selected from the group consisting of polyalkylene oxide (PAO), including polyalkylene glycol (PAG), such as linear or branched polyethylene glycol (PEG) and polypropylene glycol (PPG), poly-vinyl alcohol (PVA), poly-carboxylate, poly-(vinylpyrolidone), polyethylene-co-maleic acid anhydride, polystyrene-co-maleic acid anhydride, dextran, including carboxymethyl-dextran, or any other biopolymer suitable for reducing immunogenicity and/or increasing functional in vivo half-life and/or serum half-life. Another example of a polymer molecule is human albumin or another abundant plasma protein. Generally, polyalkylene glycol-derived polymers are biocompatible, non-toxic, non-antigenic, non-immunogenic, have various water solubility properties, and are easily excreted from living organisms.
PEG is the preferred polymer molecule, since it has only few reactive groups capable of cross-linking compared to polysaccharides such as dextran. In particular, monofunctional PEG, e.g. methoxypolyethylene glycol (mPEG), is of interest since its coupling chemistry is relatively simple (only one reactive group is available for conjugating with attachment groups on the polypeptide). Consequently, the risk of cross-linking is eliminated, the resulting polypeptide conjugates are more homogeneous and the reaction of the polymer molecules with the polypeptide is easier to control.
To effect covalent attachment of the polymer molecule(s) to the polypeptide, the hydroxyl end groups of the polymer molecule are provided in activated form, i.e. with reactive functional groups. Suitable activated polymer molecules are commercially available, e.g. from Shearwater Corp., Huntsville, Ala., USA, or from PolyMASC Pharmaceuticals plc, UK. Alternatively, the polymer molecules can be activated by conventional methods known in the art, e.g. as disclosed in WO 90/13540. Specific examples of activated linear or branched polymer molecules for use in the present invention are described in the Shearwater Corp. 1997 and 2000 Catalogs (Functionalized Biocompatible Polymers for Research and pharmaceuticals, Polyethylene Glycol and Derivatives, incorporated herein by reference). Specific examples of activated PEG polymers include the following linear PEGs: NHS-PEG (e.g. SPA-PEG, SSPA-PEG, SBA-PEG, SS-PEG, SSA-PEG, SC-PEG, SG-PEG, and SCM-PEG), and NOR-PEG), BTC-PEG, EPOX-PEG, NCO-PEG, NPC-PEG, CDI-PEG, ALD-PEG, TRES-PEG, VS-PEG, IODO-PEG, and MAL-PEG, and branched PEGs such as PEG2-NHS and those disclosed in U.S. Pat. No. 5,932,462 and U.S. Pat. No. 5,643,575, both of which are incorporated herein by reference. Furthermore, the following publications, incorporated herein by reference, disclose useful polymer molecules and/or PEGylation chemistries: U.S. Pat. Nos. 5,824,778, 5,476,653, WO 97/32607, EP 229,108, EP 402,378, U.S. Pat. Nos. 4,902,502, 5,281,698, 5,122,614, 5,219,564, WO 92/1655, WO 94/04193, WO 94/14758, WO 94/17039, WO 94/18247, WO 94/28024, WO 95/00162, WO 95/11924, WO 95/13090, WO 95/33490, WO 96/00080, WO 97/18832, WO 98/41562, WO 98/48837, WO 99/32134, WO 99/32139, WO 99/32140, WO 96/40791, WO 98/32466, WO 95/06058, EP 439 508, WO 97/03106, WO 96/21469, WO 95/13312, EP 921 131, U.S. Pat. No. 5,736,625, WO 98/05363, EP 809 996, U.S. Pat. No. 5,629,384, WO 96/41813, WO 96/07670, U.S. Pat. Nos. 5,473,034, 5,516,673, EP 605 963, U.S. Pat. No. 5,382,657, EP 510 356, EP 400 472, EP 183 503 and EP 154 316.
The conjugation of the polypeptide and the activated polymer molecules is conducted by use of any conventional method, e.g. as described in the following references (which also describe suitable methods for activation of polymer molecules): R. F. Taylor, (1991), xe2x80x9cProtein immobilisation. Fundamental and applicationsxe2x80x9d, Marcel Dekker, N.Y.; S. S. Wong, (1992), xe2x80x9cChemistry of Protein Conjugation and Crosslinkingxe2x80x9d, CRC Press, Boca Raton; G. T. Hermanson et al., (1993), xe2x80x9cImmobilized Affinity Ligand Techniquesxe2x80x9d, Academic Press, N.Y.). The skilled person will be aware that the activation method and/or conjugation chemistry to be used depends on the attachment group(s) of the polypeptide (examples of which are given further above), as well as the functional groups of the polymer (e.g. being amine, hydroxyl, carboxyl, aldehyde, sulfydryl, succinimidyl, maleimide, vinysulfone or haloacetate). The PEGylation may be directed towards conjugation to all available attachment groups on the polypeptide (i.e. such attachment groups that are exposed at the surface of the polypeptide) or may be directed towards one or more specific attachment groups, e.g. the N-terminal amino group (U.S. Pat. No. 5,985,265). Furthermore, the conjugation may be achieved in one step or in a stepwise manner (e.g. as described in WO 99/55377).
It will be understood that the PEGylation is designed so as to produce the optimal molecule with respect to the number of PEG molecules attached, the size and form of such molecules (e.g. whether they are linear or branched), and where in the polypeptide such molecules are attached. The molecular weight of the polymer to be used will be chosen taking into consideration the desired effect to be achieved. For instance, if the primary purpose of the conjugation is to achieve a conjugate having a high molecular weight and larger size (e.g. to reduce renal clearance), one may choose to conjugate either one or a few high molecular weight polymer molecules or a number of polymer molecules with a smaller molecular weight to obtain the desired effect. Preferably, however, several polymer molecules with a lower molecular weight will be used. This is also the case if a high degree of epitope shielding is desired. In such cases, 2-8 polymers with a molecular weight of e.g. about 5,000 Da, such as 3-6 such polymers, may for example be used. As the examples below illustrate, it may be advantageous to have a larger number of polymer molecules with a lower molecular weight (e.g. 4-6 with a MW of 5000) compared to a smaller number of polymer molecules with a higher molecular weight (e.g. 1-3 with a MW of 12,000-20,000) in terms of improving the functional in vivo half-life of the polypeptide conjugate, even where the total molecular weight of the attached polymer molecules in the two cases is the same or similar. It is believed that the presence of a larger number of smaller polymer molecules provides the polypeptide with a larger diameter or apparent size than e.g. a single yet larger polymer molecule, at least when the polymer molecules are relatively uniformly distributed on the polypeptide surface.
It has further been found that advantageous results are obtained when the apparent size (also referred to as the xe2x80x9capparent molecular weightxe2x80x9d or xe2x80x9capparent massxe2x80x9d) of at least a major portion of the conjugate of the invention is at least about 50 kDa, preferably at least about 55 kDa, more preferably at least about 60 kDa, e.g. at least about 66 kDa. This is believed to be due to the fact that renal clearance is substantially eliminated for conjugates having a sufficiently large apparent size. In the present context, the xe2x80x9capparent sizexe2x80x9d of a G-CSF conjugate or polypeptide is determined by the SDS-PAGE method described in the examples section below.
The use of the term xe2x80x9cmajor portionxe2x80x9d is related to the fact that the polypeptide conjugates of the invention will typically comprise individual conjugates having varying numbers of non-polypeptide moieties attached. For example, a given polypeptide subjected to PEGylation under a given set of PEGylation conditions may result in a composition in which most of the individual polypeptide conjugates have e.g. between 3 and 5 PEG groups attached, with a majority of the conjugates having 4 PEG groups attached. It will be clear that the apparent molecular weight of these individual conjugate molecules will vary. In this example, if we assume that a G-CSF polypeptide is conjugated to PEG groups with a MW of 5 kDa, conjugates having only 3 PEG groups attached will be seen on an SDS-PAGE gel as a band that is likely to have an apparent molecular weight of less than about 50 kDa, while conjugates having 4 or 5 PEG groups attached will result in bands with progressively higher apparent molecular weights that most likely all are greater than about 50 kDa. Thus, in this example there would be 3 major bands on an SDS-PAGE gel, corresponding to conjugates with 3, 4 or 5 attached PEG groups, respectively. The term xe2x80x9cmajor portionxe2x80x9d in the context of the present specification and claims is therefore intended to refer to the fact that at least one of these major bands on an SDS-PAGE gel will correspond to the indicated minimum apparent molecular weight.
Preferably, at least 50% of the individual conjugate molecules will have a minimum apparent size as described above. More preferably, at least 60% of the individual conjugate molecules with have such a minimum apparent size, still more preferably at least 70%, 75%, 80% or 85%. Most preferably, at least 90% of the individual conjugate molecules will have a minimum apparent size as described above, i.e. at least 50 kDa and preferably higher, such as at least 55 kDa or 60 kDa.
It will be understood that the apparent size in kDa of a conjugate or polypeptide is not necessarily the same as the actual molecular weight of the conjugate or polypeptide. Rather, the apparent size is a reflection of both the actual molecular weight and the overall bulk. Since, in most cases, attachment of one or more PEG groups or other non-polypeptide moieties will result in a relatively large increase of the bulk of the polypeptide to which such moieties are attached, the polypeptide conjugates of the invention will normally have an apparent size that exceeds the actual molecular weight of the conjugate. Therefore, in connection with renal clearance, a conjugate of the invention can easily exhibit properties characteristic of a is polypeptide with a molecular weight above e.g. 66 kDa (corresponding to the apparent size) but have an actual molecular weight well below 66 kDa. This effect on apparent size is believed to be responsible for the observation that attachment of, for example, four PEG groups each having a molecular weight of 5 kDa provides results that are superior to a corresponding polypeptide with a single 20 kDa PEG group attached.
While conjugation of only a single polymer molecule to a single attachment group on the protein is not preferred, in the event that only one polymer molecule is attached, it will generally be advantageous that the polymer molecule, which may be linear or branched, has a relatively high molecular weight, e.g. about 20 kDa.
In a further preferred embodiment, the conjugates of the invention have 1) at least a major portion with an apparent molecular weight of at least about 50 kDa and 2) a reduced in vitro bioactivity (reduced receptor binding affinity) compared to hG-CSF as described above. It has been found that such conjugates have both a low renal clearance as a result of the large apparent size and a low receptor-mediated clearance as a result of the low in vitro bioactivity (low receptor binding affinity). The overall result is excellent performance in terms of effective stimulation of neutrophils together with a significantly increased in vivo half-life and thus a long duration of action that provides important clinical advantages.
Normally, the polymer conjugation is performed under conditions aiming at reacting as many of the available polymer attachment groups as possible with polymer molecules. This is achieved by means of a suitable molar excess of the polymer in relation to the polypeptide (number of attachment sites). Typical molar ratios of activated polymer molecules to polypeptide attachment sites are up to about 1000-1, such as up to about 200-1 or up to about1 100-1. In some cases, the ratio may be somewhat lower, however, such as up to about 50-1, 10-1 or 5-1, e.g. if a lower degree of polymer attachment is desired.
It is also contemplated according to the invention to couple the polymer molecules to the polypeptide through a linker. Suitable linkers are well known to the skilled person. A preferred example is cyanuric chloride (Abuchowski et al., (1977), J. Biol. Chem., 252, 3578-3581; U.S. Pat. No. 4,179,337; Shafer et al., (1986), J. Polym. Sci. Polym. Chem. Ed., 24, 375-378.
Subsequent to the conjugation residual activated polymer molecules are blocked according to methods known in the art, e.g. by addition of primary amine to the reaction mixture, and the resulting inactivated polymer molecules are removed by a suitable method (see Materials and Methods).
In a preferred embodiment, the polypeptide conjugate of the invention comprises a PEG molecule attached to some, most or preferably substantially all of the lysine residues in the polypeptide available for PEGylation, in particular a linear or branched PEG molecule, e.g. with a molecular weight of about 1-15 kDa, typically about 2-12 kDa, such as about 3-10 kDa, e.g. about 5 or 6 kDa.
It will be understood that depending on the circumstances, e.g. the amino acid sequence of the polypeptide, the nature of the activated PEG compound being used and the specific PEGylation conditions, including the molar ratio of PEG to polypeptide, varying degrees of PEGylation may be obtained, with a higher degree of PEGylation generally being obtained with a higher ratio of PEG to polypeptide. The PEGylated polypeptides resulting from any given PEGylation process will, however, normally comprise a stochastic distribution of polypeptide conjugates having slightly different degrees of PEGylation. If desired, such a mixture of polypeptide species having different numbers of PEG moieties attached may be subjected to purification, e.g. using the methods described in the examples below, to obtain a product having a more uniform degree of PEGylation.
In yet another embodiment, the polypeptide conjugate of the invention may comprise a PEG molecule attached to the lysine residues in the polypeptide available for PEGylation, and in addition to the N-terminal amino acid residue of the polypeptide.
Coupling to an Oligosaccharide Moiety
The conjugation to an oligosaccharide moiety may take place in vivo or in vitro. In order to achieve in vivo glycosylation of a G-CSF molecule comprising one or more glycosylation sites the nucleotide sequence encoding the polypeptide must be inserted in a glycosylating, eukaryotic expression host. The expression host cell may be selected from fungal (filamentous fungal or yeast), insect or animal cells or from transgenic plant cells. In one embodiment the host cell is a mammalian cell, such as a CHO cell, BHK or HEK, e.g. HEK 293, cell, or an insect cell, such as an SF9 cell, or a yeast cell, e.g. S. cerevisiae or Pichia pastoris, or any of the host cells mentioned hereinafter. Covalent in vitro coupling of glycosides (such as dextran) to amino acid residues of the polypeptide may also be used, e.g. as described in WO 87/05330 and in Aplin et al., CRC Crit Rev. Biochem., pp. 259-306, 1981.
The in vitro coupling of oligosaccharide moieties or PEG to protein- and peptide-bound Gln-residues can be carried out by transglutaminases (TG""ases). Transglutaminases catalyze the transfer of donor amine-groups to protein- and peptide-bound Gln-residues in a so-called cross-linking reaction. The donor-amine groups can be protein- or peptide-bound e.g. as the c-amino-group in Lys-residues or can be part of a small or large organic molecule. An example of a small organic molecule functioning as an amino-donor in TG""ase-catalyzed cross-linking is putrescine (1,4-diaminobutane). An example of a larger organic molecule functioning as an amino-donor in TG""ase-catalyzed cross-linking is an amine-containing PEG (Sato et al., Biochemistry 35, 13072-13080).
TG""ases are in general highly specific enzymes, and not every Gln-residue exposed on the surface of a protein is accessible to TG""ase-catalyzed cross-linking to amino-containing substances. On the contrary, only a few Gln-residues function naturally as TG""ase substrates, but the exact parameters governing which Gln-residues are good TG""ase substrates remain unknown. Thus, in order to render a protein susceptible to TG""ase-catalyzed cross-linking reactions it is often a prerequisite to add at convenient positions stretches of amino acid sequence known to function very well as TG""ase substrates. Several amino acid sequences are known to be or to contain excellent natural TG""ase substrates e.g. substance P, elafin, fibrinogen, fibronectin, xcex12-plasmin inhibitor, xcex1-caseins, and xcex2-caseins.
Coupling to an Organic Derivatizing Agent
Covalent modification of the polypeptide exhibiting G-CSF activity may be performed by reacting one or more attachment groups of the polypeptide with an organic derivatizing agent. Suitable derivatizing agents and methods are well known in the art. For example, cysteinyl residues most commonly are reacted with xcex1-haloacetates (and corresponding amines), such as chloroacetic acid or chloroacetamide, to give carboxymethyl or carboxyamidomethyl derivatives. Cysteinyl residues also are derivatized by reaction with bromotrifluoroacetone, xcex1-bromo-xcex2-(4-imidozoyl)propionic acid, chloroacetyl phosphate, N-alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4-nitrophenol, or chloro-7-nitrobenzo-2-oxa-1,3-diazole. Histidyl residues are derivatized by reaction with diethylpyrocarbonateat pH 5.5-7.0 because this agent is relatively specific for the histidyl side chain. Para-bromophenacyl bromide is also useful. The reaction is preferably performed in 0.1 M sodium cacodylate at pH 6.0. Lysinyl and amino terminal residues are reacted with succinic or other carboxylic acid anhydrides. Derivatization with these agents has the effect of reversing the charge of the lysinyl residues. Other suitable reagents for derivatizing xcex1-amino-containing residues include imidoesters such as methyl picolinimidate, pyridoxal phosphate, pyridoxal, chloroborohydride, trinitrobenzenesulfonic acid, O-methylisourea, 2,4-pentanedione and transaminase-catalyzed reaction with glyoxylate. Arginyl residues are modified by reaction with one or several conventional reagents, among them phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione, and ninhydrin. Derivatization of arginine residues requires that the reaction be performed in alkaline conditions because of the high pKa of the guanidine functional group.
Furthermore, these reagents may react with the groups of lysine as well as the arginine guanidino group. Carboxyl side groups (aspartyl or glutamyl) are selectively modified by reaction with carbodiimides (Rxe2x80x94Nxe2x95x90Cxe2x95x90Nxe2x80x94Rxe2x80x2), where R and Rxe2x80x2 are different alkyl groups, such as 1-cyclohexyl-3-(2-morpholinyl-4-ethyl) carbodiimide or 1-ethyl-3-(4-azonia-4,4-dimethylpentyl) carbodiimide. Furthermore, aspartyl and glutamyl residues are converted to asparaginyl and glutaminyl residues by reaction with ammonium ions.
Blocking of the Functional Site
It has been reported that excessive polymer conjugation can lead to a loss of activity of the polypeptide to which the polymer is conjugated. This problem can be eliminated by e.g. removal of attachment groups located at the functional site or by blocking the functional site prior to conjugation so that the functional site is blocked during conjugation. The latter strategy constitutes a further embodiment of the invention (the first strategy being exemplified further above, e.g. by removal of lysine residues which may be located close to the functional site). More specifically, according to the second strategy the conjugation between the polypeptide and the non-polypeptide moiety is conducted under conditions where the functional site of the polypeptide is blocked by a helper molecule capable of binding to the functional site of the polypeptide.
Preferably, the helper molecule is one which specifically recognizes a functional site of the polypeptide, such as a receptor, in particular the G-CSF receptor or a part of the G-CSF receptor.
Alternatively, the helper molecule may be an antibody, in particular a monoclonal antibody recognizing the polypeptide exhibiting G-CSF activity. In particular, the helper molecule may be a neutralizing monoclonal antibody.
The polypeptide is allowed to interact with the helper molecule before effecting conjugation. This ensures that the functional site of the polypeptide is shielded or protected and consequently unavailable for derivatization by the non-polypeptide moiety such as a polymer. Following its elution from the helper molecule, the conjugate between the non-polypeptide moiety and the polypeptide can be recovered with at least a partially preserved functional site.
The subsequent conjugation of the polypeptide having a blocked functional site to a polymer, a lipophilic compound, an oligosaccharide moiety, an organic derivatizing agent or any other compound is conducted in the normal way, e.g. as described in the sections above entitled xe2x80x9cConjugation to . . . xe2x80x9d.
Irrespective of the nature of the helper molecule to be used to shield the functional site of the polypeptide from conjugation, it is desirable that the helper molecule is free of or comprises only a few attachment groups for the non-polypeptide moiety of choice in part(s) of the molecule where the conjugation to such groups would hamper desorption of the conjugated polypeptide from the helper molecule. Hereby, selective conjugation to attachment groups present in non-shielded parts of the polypeptide can be obtained and it is possible to reuse the helper molecule for repeated cycles of conjugation. For instance, if the non-polypeptide moiety is a polymer molecule such as PEG, which has the epsilon amino group of a lysine or N-terminal amino acid residue as an attachment group, it is desirable that the helper molecule is substantially free of conjugatable epsilon amino groups, preferably free of any epsilon amino groups. Accordingly, in a preferred embodiment the helper molecule is a protein or peptide capable of binding to the functional site of the polypeptide, which protein or peptide is free of any conjugatable attachment groups for the non-polypeptide moiety of choice.
Of particular interest in connection with the embodiment of the present invention wherein the polypeptide conjugates are prepared from a diversified population of nucleotide sequences encoding a polypeptide of interest, the blocking of the functional group is effected in microtiter plates prior to conjugation, for instance by plating the expressed polypeptide variant in a microtiter plate containing an immobilized blocking group such as a receptor, an antibody or the like.
In a further embodiment the helper molecule is first covalently linked to a solid phase such as column packing materials, for instance Sephadex or agarose beads, or a surface, e.g. a reaction vessel. Subsequently, the polypeptide is loaded onto the column material carrying the helper molecule and conjugation carried out according to methods known in the art, e.g. as described in the sections above entitled xe2x80x9cConjugation to . . . xe2x80x9d. This procedure allows the polypeptide conjugate to be separated from the helper molecule by elution. The polypeptide conjugate is eluted by conventional techniques under physico-chemical conditions that do not lead to a substantive degradation of the polypeptide conjugate. The fluid phase containing the polypeptide conjugate is separated from the solid phase to which the helper molecule remains covalently linked. The separation can be achieved in other ways: For instance, the helper molecule may be derivatized with a second molecule (e.g. biotin) that can be recognized by a specific binder (e.g. streptavidin). The specific binder may be linked to a solid phase, thereby allowing the separation of the polypeptide conjugate from the helper molecule-second molecule complex through passage over a second helper-solid phase column which will retain, upon subsequent elution, the helper molecule-second molecule complex, but not the polypeptide conjugate. The polypeptide conjugate may be released from the helper molecule in any appropriate fashion. Deprotection may be achieved by providing conditions in which the helper molecule dissociates from the functional site of the G-CSF to which it is bound. For instance, a complex between an antibody to which a polymer is conjugated and an anti-idiotypic antibody can be dissociated by adjusting the pH to an acid or alkaline pH.
Conjugation of a Tagged Polypeptide
In an alternative embodiment the polypeptide is expressed as a fusion protein with a tag, i.e. an amino acid sequence or peptide stretch made up of typically 1-30, such as 1-20 amino acid residues. Besides allowing for fast and easy purification, the tag is a convenient tool for achieving conjugation between the tagged polypeptide and the non-polypeptide moiety. In particular, the tag may be used for achieving conjugation in microtiter plates or other carriers, such as paramagnetic beads, to which the tagged polypeptide can be immobilized via the tag. The conjugation to the tagged polypeptide in e.g. microtiter plates has the advantage that the tagged polypeptide can be immobilized in the microtiter plates directly from the culture broth (in principle without any purification) and subjected to conjugation. Thereby, the total number of process steps (from expression to conjugation) can be reduced. Furthermore, the tag may function as a spacer molecule, ensuring an improved accessibility to the immobilized polypeptide to be conjugated. The conjugation using a tagged polypeptide may be to any of the non-polypeptide moieties disclosed herein, e.g. to a polymer molecule such as PEG.
The identity of the specific tag to be used is not critical as long as the tag is capable of being expressed with the polypeptide and is capable of being immobilized on a suitable surface or carrier material. A number of suitable tags are commercially available, e.g. from Unizyme Laboratories, Denmark. For instance, the tag may consist of any of the following sequences:
Met-Lys-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-Gln (SEQ ID NO:5)
His-His-His-His-His-His (SEQ ID NO:9)
Met-Lys-His-His-His-His-His-His (SEQ ID NO:10)
Met-Lys-His-His-Ala-His-His-Gln-His-His (SEQ ID NO:11)
Met-Lys-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln (SEQ ID NO:12)
or any of the following:
EQKLI SEEDL (SEQ ID NO:13; a C-terminal tag described in Mol. Cell. Biol. 5:3610-16, 1985)
DYKDDDDK (SEQ ID NO:14; a C- or N-terminal tag)
YPYDVPDYA (SEQ ID NO:15)
Antibodies against the above tags are commercially available, e.g. from ADI, Aves Lab and Research Diagnostics.
A convenient method for using a tagged polypeptide for PEGylation is given in the Materials and Methods section below. The subsequent cleavage of the tag from the polypeptide may be achieved by use of commercially available enzymes.
Methods for Preparing a Polypeptide of the Invention or the Polypeptide Part of the Conjugate of the Invention
The polypeptide of the present invention or the polypeptide part of a conjugate of the invention, optionally in glycosylated form, may be produced by any suitable method known in the art. Such methods include constructing a nucleotide sequence encoding the polypeptide and expressing the sequence in a suitable transformed or transfected host. However, polypeptides of the invention may be produced, albeit less efficiently, by chemical synthesis or a combination of chemical synthesis or a combination of chemical synthesis and recombinant DNA technology.
A nucleotide sequence encoding a polypeptide or the polypeptide part of a conjugate of the invention may be constructed by isolating or synthesizing a nucleotide sequence encoding the parent G-CSF, such as hG-CSF with the amino acid sequence shown in SEQ ID NO:1, and then changing the nucleotide sequence so as to effect introduction (i.e. insertion or substitution) or deletion (i.e. removal or substitution) of the relevant amino acid residue(s).
The nucleotide sequence is conveniently modified by site-directed mutagenesis in accordance with conventional methods. Alternatively, the nucleotide sequence is prepared by chemical synthesis, e.g. by using an oligonucleotide synthesizer, wherein oligonucleotides are designed based on the amino acid sequence of the desired polypeptide, and preferably selecting those codons that are favored in the host cell in which the recombinant polypeptide will be produced. For example, several small oligonucleotides coding for portions of the desired polypeptide may be synthesized and assembled by PCR, ligation or ligation chain reaction (LCR) (Barany, PNAS 88:189-193, 1991). The individual oligonucleotides typically contain 5xe2x80x2 or 3xe2x80x2 overhangs for complementary assembly.
Alternative nucleotide sequence modification methods are available for producing polypeptide variants for high throughput screening, for instance methods which involve homologous cross-over such as disclosed in U.S. Pat. No. 5,093,257, and methods which involve gene shuffling, i.e. recombination between two or more homologous nucleotide sequences resulting in new nucleotide sequences having a number of nucleotide alterations when compared to the starting nucleotide sequences. Gene shuffling (also known as DNA shuffling) involves one or more cycles of random fragmentation and reassembly of the nucleotide sequences, followed by screening to select nucleotide sequences encoding polypeptides with desired properties. In order for homology-based nucleic acid shuffling to take place, the relevant parts of the nucleotide sequences are preferably at least 50% identical, such as at least 60% identical, more preferably at least 70% identical, such as at least 80% identical. The recombination can be performed in vitro or in vivo.
Examples of suitable in vitro gene shuffling methods are disclosed by Stemmer et al. (1994), Proc. Natl. Acad. Sci. USA; vol. 91, pp. 10747-10751; Stemmer (1994), Nature, vol. 370, pp. 389-391; Smith (1994), Nature vol. 370, pp. 324-325; Zhao et al., Nat. Biotechnol. 1998, March; 16(3): 258-61; Zhao H. and Arnold, F B, Nucleic Acids Research, 1997, Vol. 25. No. 6 pp. 1307-1308; Shao et al., Nucleic Acids Research Jan. 15, 1998; 26(2): pp. 681-83; and WO 95/17413. An example of a suitable in vivo shuffling method is disclosed in WO 97/07205. Other techniques for mutagenesis of nucleic acid sequences by in vitro or in vivo recombination are disclosed e.g. in WO 97/20078 and U.S. Pat. No. 5,837,458. Examples of specific shuffling techniques include xe2x80x9cfamily shufflingxe2x80x9d, xe2x80x9csynthetic shufflingxe2x80x9d and xe2x80x9cin silico shufflingxe2x80x9d. Family shuffling involves subjecting a family of homologous genes from different species to one or more cycles of shuffling and subsequent screening or selection. Family shuffling techniques are disclosed e.g. by Crameri et al. (1998), Nature, vol. 391, pp. 288-291; Christians et al. (1999), Nature Biotechnology, vol. 17, pp. 259-264; Chang et al. (1999), Nature Biotechnology, vol. 17, pp. 793-797; and Ness et al. (1999), Nature Biotechnology, vol. 17, 893-896. Synthetic shuffling involves providing libraries of overlapping synthetic oligonucleotides based e.g. on a sequence, alignment of homologous genes of interest. The synthetically generated oligonucleotides are recombined, and the resulting recombinant nucleic acid sequences are screened and if desired used for further shuffling cycles. Synthetic shuffling techniques are disclosed in WO 00/42561. In silico shuffling refers to a DNA shuffling procedure which is performed or modelled using a computer system, thereby partly or entirely avoiding the need for physically manipulating nucleic acids. Techniques for in silico shuffling are disclosed in WO 00/42560.
Once assembled (by synthesis, site-directed mutagenesis or another method), the nucleotide sequence encoding the polypeptide is inserted into a recombinant vector and operably linked to control sequences necessary for expression of the G-CSF in the desired transformed host cell.
It should of course be understood that not all vectors and expression control sequences function equally well to express the nucleotide sequence encoding a polypeptide described herein. Neither will all hosts function equally well with the same expression system. However, one of skill in the art may make a selection among these vectors, expression control sequences and hosts without undue experimentation. For example, in selecting a vector, the host must be considered because the vector must replicate in it or be able to integrate into the chromosome. The vector""s copy number, the ability to control that copy number, and the expression of any other proteins encoded by the vector, such as antibiotic markers, should also be considered. In selecting an expression control sequence, a variety of factors should also be considered. These include, for example, the relative strength of the sequence, its controllability, and its compatibility with the nucleotide sequence encoding the polypeptide, particularly as regards potential secondary structures. Hosts should be selected by consideration of their compatibility with the chosen vector, the toxicity of the product coded for by the nucleotide sequence, their secretion characteristics, their ability to fold the polypeptide correctly, their fermentation or culture requirements, and the ease of purification of the products coded for by the nucleotide sequence.
The recombinant vector may be an autonomously replicating vector, i.e. a vector, which exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g. a plasmid. Alternatively, the vector is one which, when introduced into a host cell, is integrated into the host cell genome and replicated together with the chromosome(s) into which it has been integrated.
The vector is preferably an expression vector in which the nucleotide sequence encoding the polypeptide of the invention is operably linked to additional segments required for transcription of the nucleotide sequence. The vector is typically derived from plasmid or viral DNA. A number of suitable expression vectors for expression in the host cells mentioned herein are commercially available or described in the literature. Useful expression vectors for eukaryotic hosts include, for example, vectors comprising expression control sequences from SV40, bovine papilloma virus, adenovirus and cytomegalovirus. Specific vectors are, e.g., pcDNA3.1(+) Hyg (Invitrogen, Carlsbad, CA, USA) and pCI-neo (Stratagene, La Jolla, CA, USA). Useful expression vectors for yeast cells include the 2xcexc plasmid and derivatives thereof, the POT1 vector (U.S. Pat. No. 4,931,373), the pJSO37 vector described in Okkels, Ann. New York Acad. Sci. 782, 202-207, 1996, and pPICZ A, B or C (Invitrogen). Useful vectors for insect cells include pVL941, pBG311 (Cate et al., xe2x80x9cIsolation of the Bovine and Human Genes for Mullerian Inhibiting Substance And Expression of the Human Gene In Animal Cellsxe2x80x9d, Cell, 45, pp. 685-98 (1986), pBluebac 4.5 and pMelbac (both available from Invitrogen). Useful expression vectors for bacterial hosts include known bacterial plasmids, such as plasmids from E. coli, including pBR322, pET3a and pET12a (both from Novagen Inc., WI, USA), wider host range plasmids, such as RP4, phage DNAs, e.g. the numerous derivatives of phage lambda, e.g. NM989, and other DNA phages, such as M13 and filamentous single stranded DNA phages.
Other vectors for use in this invention include those that allow the nucleotide sequence encoding the polypeptide to be amplified in copy number. Such amplifiable vectors are well known in the art. They include, for example, vectors able to be amplified by DHFR amplification (see, e.g., Kaufman, U.S. Pat. No. 4,470,461, Kaufman and Sharp, xe2x80x9cConstruction Of A Modular Dihydrafolate Reductase cDNA Gene: Analysis Of Signals Utilized For Efficient Expressionxe2x80x9d, Mol. Cell. Biol., 2, pp. 1304-19 (1982)) and glutamine synthetase (xe2x80x9cGSxe2x80x9d) amplification (see, e.g., U.S. Pat. No. 5,122,464 and EP 338,841).
The recombinant vector may further comprise a DNA sequence enabling the vector to replicate in the host cell in question. An example of such a sequence (when the host cell is a mammalian cell) is the SV40 origin of replication. When the host cell is a yeast cell, suitable sequences enabling the vector to replicate are the yeast plasmid 2xcexc replication genes REP 1-3 and origin of replication.
The vector may also comprise a selectable marker, e.g. a gene whose product complements a defect in the host cell, such as the gene coding for dihydrofolate reductase (DHFR) or the Schizosaccharomyces pombe TPI gene (described by P. R. Russell, Gene 40, 1985, pp. 125-130), or one which confers resistance to a drug, e.g. ampicillin, kanamycin, tetracyclin, chloramphenicol, neomycin, hygromycin or methotrexate. For Saccharomyces cerevisiae, selectable markers include ura3 and leu2. For filamentous fungi, selectable markers include amdS, pyrG, arcB, niaD and sC.
The term xe2x80x9ccontrol sequencesxe2x80x9d is defined herein to include all components which are necessary or advantageous for the expression of the polypeptide of the invention. Each control sequence may be native or foreign to the nucleic acid sequence encoding the polypeptide. Such control sequences include, but are not limited to, a leader sequence, polyadenylation sequence, propeptide sequence, promoter, enhancer or upstream activating sequence, signal peptide sequence, and transcription terminator. At a minimum, the control sequences include a promoter.
A wide variety of expression control sequences may be used in the present invention. Such useful expression control sequences include the expression control sequences associated with structural genes of the foregoing expression vectors as well as any sequence known to control the expression of genes of prokaryotic or eukaryotic cells or their viruses, and various combinations thereof.
Examples of suitable control sequences for directing transcription in mammalian cells include the early and late promoters of SV40 and adenovirus, e.g. the adenovirus 2 major late promoter, the MT-1 (metallothionein gene) promoter, the human cytomegalovirus immediate-early gene promoter (CMV), the human elongation factor 1xcex1 (EF-1xcex1) promoter, the Drosophila minimal heat shock protein 70 promoter, the Rous Sarcoma Virus (RSV) promoter, the human ubiquitin C (UbC) promoter, the human growth hormone terminator, SV40 or adenovirus E1 region polyadenylation signals and the Kozak consensus sequence (Kozak, M. J Mol Biol 1987 Aug. 20;196(4):947-50).
In order to improve expression in mammalian cells a synthetic intron may be inserted in the 5xe2x80x2 untranslated region of the nucleotide sequence encoding the polypeptide. An example of a synthetic intron is the synthetic intron from the plasmid pCI-Neo (available from Promega Corporation, WI, USA).
Examples of suitable control sequences for directing transcription in insect cells include the polyhedrin promoter, the P10 promoter, the Autographa californica polyhedrosis virus basic protein promoter, the baculovirus immediate early gene 1 promoter, the baculovirus 39K delayed-early gene promoter, and the SV40 polyadenylation sequence. Examples of suitable control sequences for use in yeast host cells include the promoters of the yeast xcex1-mating system, the yeast triose phosphate isomerase (TPI) promoter, promoters from yeast glycolytic genes or alcohol dehydrogenase genes, the ADH2-4c promoter, and the inducible GAL promoter. Examples of suitable control sequences for use in filamentous fungal host cells include the ADH3 promoter and terminator, a promoter derived from the genes encoding Aspergillus oryzae TAKA amylase triose phosphate isomerase or alkaline protease, an A. niger xcex1-amylase, A. niger or A. nidulans glucoamylase, A. nidulans acetamidase, Rhizomucor miehei aspartic proteinase or lipase, the TPI1 terminator and the ADH3 terminator. Examples of suitable control sequences for use in bacterial host cells include promoters of the lac system, the trp system, the TAC or TRC system, and the major promoter regions of phage lambda.
The presence or absence of a signal peptide will, e.g., depend on the expression host cell used for the production of the polypeptide to be expressed (whether it is an intracellular or extracellular polypeptide) and whether it is desirable to obtain secretion. For use in filamentous fungi, the signal peptide may conveniently be derived from a gene encoding an Aspergillus sp. amylase or glucoamylase, a gene encoding a Rhizomucor miehei lipase or protease or a Humicola lanuginosa lipase. The signal peptide is preferably derived from a gene encoding A. oryzae TAKA amylase, A. niger neutral xcex1-amylase, A. niger acid-stable amylase, or A. niger glucoamylase. For use in insect cells, the signal peptide may conveniently be derived from an insect gene (cf. WO 90/05783), such as the Lepidopteran manduca sexta adipokinetic hormone precursor, (cf. U.S. Pat. No. 5,023,328), the honeybee melittin (Invitrogen), ecdysteroid UDPglucosyltransferase (egt) (Murphy et al., Protein Expression and Purification 4, 349-357 (1993) or human pancreatic lipase (hpl) (Methods in Enzymology 284, pp. 262-272, 1997). A preferred signal peptide for use in mammalian cells is that of hG-CSF or the murine Ig kappa light chain signal peptide (Coloma, M (1992) J. Imm. Methods 152:89-104). For use in yeast cells suitable signal peptides have been found to be the xcex1-factor signal peptide from S. cereviciae (cf. U.S. Pat. No. 4,870,008), a modified carboxypeptidase signal peptide (cf. L. A. Valls et al., Cell 48, 1987, pp. 887-897), the yeast BAR1 signal peptide (cf. WO 87/02670), the yeast aspartic protease 3 (YAP3) signal peptide (cf. M. Egel-Mitani et al., Yeast 6, 1990, pp. 127-137), and the synthetic leader sequence TA57 (WO98/32867). For use in E. coli cells a suitable signal peptide has been found to be the signal peptide ompA.
The nucleotide sequence of the invention encoding a polypeptide exhibiting G-CSF activity, whether prepared by site-directed mutagenesis, synthesis, PCR or other methods, may optionally also include a nucleotide sequence that encodes a signal peptide. The signal peptide is present when the polypeptide is to be secreted from the cells in which it is expressed. Such signal peptide, if present, should be one recognized by the cell chosen for expression of the polypeptide. The signal peptide may be homologous (e.g. be that normally associated with hG-CSF) or heterologous (i.e. originating from another source than hG-CSF) to the polypeptide or may be homologous or heterologous to the host cell, i.e. be a signal peptide normally expressed from the host cell or one which is not normally expressed from the host cell. Accordingly, the signal peptide may be prokaryotic, e.g. derived from a bacterium such as E. coli, or eukaryotic, e.g. derived from a mammalian, or insect or yeast cell.
Any suitable host may be used to produce the polypeptide or polypeptide part of the conjugate of the invention, including bacteria, fungi (including yeasts), plant, insect, mammal, or other appropriate animal cells or cell lines, as well as transgenic animals or plants. Examples of bacterial host cells include gram-positive bacteria such as strains of Bacillus, e.g. B. brevis or B. subtilis, or Streptomyces, or gram-negative bacteria, such as strains of E. coli or Pseudomonas. The introduction of a vector into a bacterial host cell may, for instance, be effected by protoplast transformation (see, e.g., Chang and Cohen, 1979, Molecular General Genetics 168: 111-115), using competent cells (see, e.g., Young and Spizizin, 1961, Journal of Bacteriology 81: 823-829, or Dubnau and Davidoff-Abelson, 1971, Journal of Molecular Biology 56: 209-221), electroporation (see, e.g., Shigekawa and Dower, 1988, Biotechniques 6: 742-751), or conjugation (see, e.g., Koehler and Thome, 1987, Journal of Bacteriology 169: 5771-5278). Examples of suitable filamentous fungal host cells include strains of Aspergillus, e.g. A. oryzae, A. niger, or A. nidulans, Fusarium or Trichoderma. Fungal cells may be transformed by a process involving protoplast formation, transformation of the protoplasts, and regeneration of the cell wall in a manner known per se. Suitable procedures for transformation of Aspergillus host cells are described in EP 238 023 and U.S. Pat. No. 5,679,543. Suitable methods for transforming Fusarium species are described by Malardier et al., 1989, Gene 78: 147-156 and WO 96/00787. Examples of suitable yeast host cells include strains of Saccharomyces, e.g. S. cerevisiae, Schizosaccharomyces, Klyveromyces, Pichia, such as P. pastoris or P. methanolica, Hansenula, such as H. polymorpha or Yarrowia. Yeast may be transformed using the procedures described by Becker and Guarente, In Abelson, J. N. and Simon, M. I., editors, Guide to Yeast Genetics and Molecular Biology, Methods in Enzymology, Volume 194, pp 182-187, Academic Press, Inc., New York; Ito et al., 1983, Journal of Bacteriology 153: 163; Hinnen et al., 1978, Proceedings of the National Academy of Sciences USA 75: 1920: and as disclosed by Clontech Laboratories, Inc, Palo Alto, Calif., USA (in the product protocol for the Yeastmaker(trademark) Yeast Transformation System Kit). Examples of suitable insect host cells include a Lepidoptora cell line, such as Spodoptera frugiperda (Sf9 or Sf21) or Trichoplusioa ni cells (High Five) (U.S. Pat. No. 5,077,214). Transformation of insect cells and production of heterologous polypeptides therein may be performed as described by Invitrogen. Examples of suitable mammalian host cells include Chinese hamster ovary (CHO) cell lines, (e.g. CHO-K1; ATCC CCL-61), Green Monkey cell lines (COS) (e.g. COS 1 (ATCC CRL-1650), COS 7 (ATCC CRL-1651)); mouse cells (e.g. NS/O), Baby Hamster Kidney (BHK) cell lines (e.g. ATCC CRL-1632 or ATCC CCL-10), and human cells (e.g. HEK 293 (ATCC CRL-1573)), as well as plant cells in tissue culture. Additional suitable cell lines are known in the art and available from public depositories such as the American Type Culture Collection, Rockville, Md. Methods for introducing exogeneous DNA into mammalian host cells include calcium phosphate-mediated transfection, electroporation, DEAE-dextran mediated transfection, liposome-mediated transfection, viral vectors and the transfection method described by Life Technologies Ltd, Paisley, UK using Lipofectamin 2000. These methods are well known in the art and e.g. described by Ausbel et al. (eds.), 1996, Current Protocols in Molecular Biology, John Wiley and Sons, New York, USA. The cultivation of mammalian cells is conducted according to established methods, e.g. as disclosed in (Animal Cell Biotechnology, Methods and Protocols, Edited by Nigel Jenkins, 1999, Human Press Inc, Totowa, N.J., USA and Harrison M A and Rae I F, General Techniques of Cell Culture, Cambridge University Press 1997).
In the production methods of the present invention, the cells are cultivated in a nutrient medium suitable for production of the polypeptide using methods known in the art. For example, the cell may be cultivated by shake flask cultivation, small-scale or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermenters performed in a suitable medium and under conditions allowing the polypeptide to be expressed and/or isolated. The cultivation takes place in a suitable nutrient medium comprising carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). If the polypeptide is secreted into the nutrient medium, the polypeptide can be recovered directly from the medium. If the polypeptide is not secreted, it can be recovered from cell lysates.
The resulting polypeptide may be recovered by methods known in the art. For example, the polypeptide may be recovered from the nutrient medium by conventional procedures including, but not limited to, centrifugation, filtration, extraction, spray drying, evaporation, or precipitation.
The polypeptides may be purified by a variety of procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g., Protein Purification, J.-C. Janson and Lars Ryden, editors, VCH Publishers, New York, 1989). Specific methods for purifying polypeptides exhibiting G-CSF activity are described by D. Metcalf and N. A. Nicola in The hemopoietic colony-stimulating factors, p. 50-51, Cambridge University Press (1995), by C. S. Bae et al., Appl. Microbiol. Biotechnol, 52:338-344 (1999) and in U.S. Pat. No. 4,810,643.
Pharmaceutical Composition of the Invention and its Use
In a further aspect, the present invention comprises a composition comprising a polypeptide or conjugate as described herein and at least one pharmaceutically acceptable carrier or excipient.
The polypeptide, the conjugate or the pharmaceutical composition according to the invention may be used for the manufacture of a medicament for treatment of diseases, in particular prevention of infection in cancer patients undergoing certain types of chemotherapy, radiation therapy and bone marrow transplantations, mobilisation of progenitor cells for collection in peripheral blood progenitor cell transplantations, treatment of severe chronic or relative leukopenia, treatment of patients with acute mycloid leukaemia, treatment of AIDS or other immunodeficiency diseases, and for antifungal therapy, in particular for treatment of systemic or invasive candidiasis.
In another aspect the polypeptide, the conjugate or the pharmaceutical composition according to the invention is used in a method of treating a mammal having a general haematopoietic disorder, including those arising from radiation therapy or from chemotherapy, in particular neutropenia or leukopenia, AIDS or other immunodeficiency diseases, comprising administering to a mammal in need thereof such a polypeptide, conjugate or pharmaceutical composition. In particular, the method is aimed at increasing the level of neutrophils in a patient suffering from an insufficient neutrophil level, for example due to chemotherapy, radiation therapy, or HIV or another viral infection.
The polypeptides and conjugates of the invention will be administered to patients in a xe2x80x9ctherapeutically effectivexe2x80x9d dose, i.e. a dose that is sufficient to produced the desired effects in relation to the condition for which it is administered. The exact dose will depend on the disorder to be treated, and will be ascertainable by one skilled in the art using known techniques. The polypeptides or conjugates of the invention may e.g. be administered at a dose similar to that employed in therapy with rhG-CSF such as Neupogen(copyright). A suitable dose of a conjugate of the invention is contemplated to be in the range of about 5-300 microgram/kg body weight (based on the weight of the protein part of the conjugate), e.g. 10-200 microgram/kg, such as 25-100 microgram/kg. It will be apparent to those of skill in the art that an effective amount of a polypeptide, conjugate or composition of the invention depends, inter alia, upon the disease, the dose, the administration schedule, whether the polypeptide or conjugate or composition is administered alone or in conjunction with other therapeutic agents, the serum half-life of the compositions, the general health of the patient, and the frequency of administration. Preferably, the polypeptide, conjugate, preparation or composition of the invention is administered in an effective dose, in particular a dose which is sufficient to normalize the number of leukocytes, in particular neutrophils, in the patient in question. Normalization of the number of leukocytes may be determined by simply counting the number of leukocytes at regular intervals in accordance with established practice.
The polypeptide or conjugate of the invention is preferably administered in a composition including one or more pharmaceutically acceptable carriers or excipients. The polypeptide or conjugate can be formulated into pharmaceutical compositions in a manner known per se in the art to result in a polypeptide pharmaceutical that is sufficiently storage-stable and is suitable for administration to humans or animals. The pharmaceutical composition may be formulated in a variety of forms, including as a liquid or gel, or lyophilized, or any other suitable form. The preferred form will depend upon the particular indication being treated and will be apparent to one of skill in the art.
Accordingly, this invention provides compositions and methods for treating various forms of leukopenia or neutropenia. In particular the polypeptide, conjugate or composition of the invention may be used to prevent infection in cancer patients undergoing certain types of radiation therapy chemotherapy and bone marrow transplantations, to mobilize progenitor cells for collection in peripheral blood progenitor cell transplantations, for treatment of severe chronic or relative leukopenia and to support treatment of patients with acute myeloid leukaemia. Additionally, the polypeptide, conjugate or composition of the invention may be used for treatment of AIDS or other immunodeficiency diseases and for antifungal therapy, in particular for treament of systemic or invasive candidiasis, and for the treatment of bacterial infections.
Since the polypeptide conjugates of the invention have a long in vivo half-life and have been found to reduce the duration of neutropenia and leukopenia by administration of a single dose, in contrast to hG-CSF which must be administered daily, the conjugates of the invention are well-suited for administration e.g. on a weekly basis for the prevention and/or treatment of neutropenia. In one embodiment, the polypeptide conjugate or pharmaceutical composition of the invention is for the prevention and/or treatment of neutropenia due to chemotherapy. In the case of chemotherapy administered at intervals, e.g. on a weekly basis by intravenous injection or by another type of injection, such as subcutaneous or intramuscular injection, it will normally be sufficient to administer the conjugate of the invention in a single dose per chemotherapy treatment, i.e. given either before, after or simultaneously with the chemotherapy. In other cases where the chemotherapy is administered differently, for example orally on a daily basis or over an extended period of time by means of an infusion pump, the conjugates of the invention may be administered in a similar manner, e.g. once a week, or, in the case of chemotherapy sessions given less frequently than once a week, once per session.
Drug Form
The polypeptide or conjugate of the invention can be used xe2x80x9cas isxe2x80x9d and/or in a salt form thereof. Suitable salts include, but are not limited to, salts with alkali metals or alkaline earth metals, such as sodium, potassium, calcium and magnesium, as well as e.g. zinc salts. These salts or complexes may by present as a crystalline and/or amorphous structure.
Excipients
xe2x80x9cPharmaceutically acceptablexe2x80x9d means a carrier or excipient that at the dosages and concentrations employed does not cause any untoward effects in the patients to whom it is administered. Such pharmaceutically acceptable carriers and excipients are well known in the art (see Remington""s Pharmaceutical Sciences, 18th edition, A. R. Gennaro, Ed., Mack Publishing Company [1990]; Pharmaceutical Formulation Development of Peptides and Proteins, S. Frokjaer and L. Hovgaard, Eds., Taylor and Francis [2000]; and Handbook of Pharmaceutical Excipients, 3rd edition, A. Kibbe, Ed., Pharmaceutical Press [2000]).
Mix of Drugs
The pharmaceutical composition of the invention may be administered alone or in conjunction with other therapeutic agents. These agents may be incorporated as part of the same pharmaceutical composition or may be administered separately from the polypeptide or conjugate of the invention, either concurrently or in accordance with another treatment schedule. In addition, the polypeptide, conjugate or pharmaceutical composition of the invention may be used as an adjuvant to other therapies.
Patients
A xe2x80x9cpatientxe2x80x9d for the purposes of the present invention includes both humans and other mammals. Thus the methods are applicable to both human therapy and veterinary applications.
Administration Route
The administration of the formulations of the present invention can be performed in a variety of ways, including, but not limited to, orally, subcutaneously, intravenously, intracerebrally, intranasally, transdermally, intraperitoneally, intramuscularly, intrapulmonary, vaginally, rectally, intraocularly, or in any other acceptable manner. The formulations can be administered continuously by infusion, although bolus injection is acceptable, using techniques well known in the art. Typically, the formulation will designed for parenteral administration, e.g. by the subcutaneous route.
Parenterals
An example of a pharmaceutical composition is a solution designed for parenteral administration. Although in many cases pharmaceutical solution formulations are provided in liquid form, appropriate for immediate use, such parenteral formulations may also be provided in frozen or in lyophilized form. In the former case, the composition must be thawed prior to use. The latter form is often used to enhance the stability of the active compound contained in the composition under a wider variety of storage conditions, as it is recognized by those skilled in the art that lyophilized preparations are generally more stable than their liquid counterparts. Such lyophilized preparations are reconstituted prior to use by the addition of one or more suitable pharmaceutically acceptable diluents such as sterile water for injection or sterile physiological saline solution.
In case of parenterals, they are prepared for storage as lyophilized formulations or aqueous solutions by mixing, as appropriate, the polypeptide having the desired degree of purity with one or more pharmaceutically acceptable carriers, excipients or stabilizers typically employed in the art (all of which are termed xe2x80x9cexcipientsxe2x80x9d), for example buffering agents, stabilizing agents, preservatives, isotonifiers, non-ionic detergents, antioxidants and/or other miscellaneous additives.
Buffering agents help to maintain the pH in the range which approximates physiological conditions. They are typically present at a concentration ranging from about 2 mM to about 50 mM Suitable buffering agents for use with the present invention include both organic and inorganic acids and salts thereof such as citrate buffers (e.g., monosodium citrate-disodium citrate mixture, citric acid-trisodium citrate mixture, citric acid-monosodium citrate mixture, etc.), succinate buffers (e.g., succinic acid-monosodium succinate mixture, succinic acid-sodium hydroxide mixture, succinic acid-disodium succinate mixture, etc.), tartrate buffers (e.g., tartaric acid-sodium tartrate mixture, tartaric acid-potassium tartrate mixture, tartaric acid-sodium hydroxide mixture, etc.), fumarate buffers (e.g., fumaric acid-monosodium fumarate mixture, fumaric acid-di sodium fumarate mixture, monosodium fumarate-di sodium fumarate mixture, etc.), gluconate buffers (e.g., gluconic acid-sodium glyconate mixture, gluconic acid-sodium hydroxide mixture, gluconic acid-potassium glyuconate mixture, etc.), oxalate buffer (e.g., oxalic acid-sodium oxalate mixture, oxalic acid-sodium hydroxide mixture, oxalic acid-potassium oxalate mixture, etc.), lactate buffers (e.g., lactic acid-sodium lactate mixture, lactic acid-sodium hydroxide mixture, lactic acid-potassium lactate mixture, etc.) and acetate buffers (e.g., acetic acid-sodium acetate mixture, acetic acid-sodium hydroxide mixture, etc.). Additional possibilities are phosphate buffers, histidine buffers and trimethylamine salts such as Tris.
Preservatives are added to retard microbial growth, and are typically added in amounts of about 0.2%-1% (w/v). Suitable preservatives for use with the present invention include phenol, benzyl alcohol, meta-cresol, methyl paraben, propyl paraben, octadecyldimethylbenzyl ammonium chloride, benzalkonium halides (e.g. benzalkonium chloride, bromide or iodide), hexamethonium chloride, alkyl parabens such as methyl or propyl paraben, catechol, resorcinol, cyclohexanol and 3-pentanol.
Isotonicifiers are added to ensure isotonicity of liquid compositions and include polyhydric sugar alcohols, preferably trihydric or higher sugar alcohols, such as glycerin, erythritol, arabitol, xylitol, sorbitol and mannitol. Polyhydric alcohols can be present in an amount between 0.1% and 25% by weight, typically 1% to 5%, taking into account the relative amounts of the other ingredients.
Stabilizers refer to a broad category of excipients which can range in function from a bulking agent to an additive which solubilizes the therapeutic agent or helps to prevent denaturation or adherence to the container wall. Typical stabilizers can be polyhydric sugar alcohols (enumerated above); amino acids such as arginine, lysine, glycine, glutamine, asparagine, histidine, alanine, omithine, L-leucine, 2-phenylalanine, glutamic acid, threonine, etc., organic sugars or sugar alcohols, such as lactose, trehalose, stachyose, mannitol, sorbitol, xylitol, ribitol, myoinisitol, galactitol, glycerol and the like, including cyclitols such as inositol; polyethylene glycol; amino acid polymers; sulfur-containing reducing agents, such as urea, glutathione, thioctic acid, sodium thioglycolate, thioglycerol, a-monothioglycerol and sodium thiosulfate; low molecular weight polypeptides (i.e.  less than 10 residues); proteins such as human serum albumin, bovine serum albumin, gelatin or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; monosaccharides such as xylose, mannose, fructose and glucose; disaccharides such as lactose, maltose and sucrose; trisaccharides such as raffinose, and polysaccharides such as dextran. Stabilizers are typically present in the range of from 0.1 to 10,000 parts by weight based on the active protein weight.
Non-ionic surfactants or detergents (also known as xe2x80x9cwetting agentsxe2x80x9d) may be present to help solubilize the therapeutic agent as well as to protect the therapeutic polypeptide against agitation-induced aggregation, which also permits the formulation to be exposed to shear surface stress without causing denaturation of the polypeptide. Suitable non-ionic surfactants include polysorbates (20, 80, etc.), polyoxamers (184, 188 etc.), Pluronic(copyright) polyols, polyoxyethylene sorbitan monoethers (Tween(copyright)-20, Tween(copyright)-80, etc.).
Additional miscellaneous excipients include bulking agents or fillers (e.g. starch), chelating agents (e.g. EDTA), antioxidants (e.g., ascorbic acid, methionine, vitamin E) and cosolvents.
The active ingredient may also be entrapped in microcapsules prepared, for example, by coascervation techniques or by interfacial polymerization, for example hydroxymethylcellulose, gelatin or poly-(methylmethacylate) microcapsules, in colloidal drug delivery systems (for example liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington""s Pharmaceutical Sciences, supra.
Parenteral formulations to be used for in vivo administration must be sterile. This is readily accomplished, for example, by filtration through sterile filtration membranes.
Sustained Release Preparations
Suitable examples of sustained-release preparations include semi-permeable matrices of solid hydrophobic polymers containing the polypeptide or conjugate, the matrices having a suitable form such as a film or microcapsules. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate) or poly(vinylalcohol)), polylactides, copolymers of L-glutamic acid and ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the ProLease(copyright) technology or Lupron Depot(copyright) (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(xe2x88x92)-3-hydroxybutyric acid. While polymers such as ethylene-vinyl acetate and lactic acid-glycolic acid enable release of molecules for long periods such as up to or over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated polypeptides remain in the body for a long time, they may denature or aggregate as a result of exposure to moisture at 37xc2x0 C., resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular Sxe2x80x94S bond formation through thio-disulfide interchange, stabilization may be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing specific polymer matrix compositions.
All references cited herein are hereby incorporated by reference in their entirety for all purposes.
The invention is further described in the non-limiting examples below.